mirror of
https://github.com/torvalds/linux.git
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3822a7c409
F_SEAL_EXEC") which permits the setting of the memfd execute bit at memfd creation time, with the option of sealing the state of the X bit. - Peter Xu adds a patch series ("mm/hugetlb: Make huge_pte_offset() thread-safe for pmd unshare") which addresses a rare race condition related to PMD unsharing. - Several folioification patch serieses from Matthew Wilcox, Vishal Moola, Sidhartha Kumar and Lorenzo Stoakes - Johannes Weiner has a series ("mm: push down lock_page_memcg()") which does perform some memcg maintenance and cleanup work. - SeongJae Park has added DAMOS filtering to DAMON, with the series "mm/damon/core: implement damos filter". These filters provide users with finer-grained control over DAMOS's actions. SeongJae has also done some DAMON cleanup work. - Kairui Song adds a series ("Clean up and fixes for swap"). - Vernon Yang contributed the series "Clean up and refinement for maple tree". - Yu Zhao has contributed the "mm: multi-gen LRU: memcg LRU" series. It adds to MGLRU an LRU of memcgs, to improve the scalability of global reclaim. - David Hildenbrand has added some userfaultfd cleanup work in the series "mm: uffd-wp + change_protection() cleanups". - Christoph Hellwig has removed the generic_writepages() library function in the series "remove generic_writepages". - Baolin Wang has performed some maintenance on the compaction code in his series "Some small improvements for compaction". - Sidhartha Kumar is doing some maintenance work on struct page in his series "Get rid of tail page fields". - David Hildenbrand contributed some cleanup, bugfixing and generalization of pte management and of pte debugging in his series "mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on all architectures with swap PTEs". - Mel Gorman and Neil Brown have removed the __GFP_ATOMIC allocation flag in the series "Discard __GFP_ATOMIC". - Sergey Senozhatsky has improved zsmalloc's memory utilization with his series "zsmalloc: make zspage chain size configurable". - Joey Gouly has added prctl() support for prohibiting the creation of writeable+executable mappings. The previous BPF-based approach had shortcomings. See "mm: In-kernel support for memory-deny-write-execute (MDWE)". - Waiman Long did some kmemleak cleanup and bugfixing in the series "mm/kmemleak: Simplify kmemleak_cond_resched() & fix UAF". - T.J. Alumbaugh has contributed some MGLRU cleanup work in his series "mm: multi-gen LRU: improve". - Jiaqi Yan has provided some enhancements to our memory error statistics reporting, mainly by presenting the statistics on a per-node basis. See the series "Introduce per NUMA node memory error statistics". - Mel Gorman has a second and hopefully final shot at fixing a CPU-hog regression in compaction via his series "Fix excessive CPU usage during compaction". - Christoph Hellwig does some vmalloc maintenance work in the series "cleanup vfree and vunmap". - Christoph Hellwig has removed block_device_operations.rw_page() in ths series "remove ->rw_page". - We get some maple_tree improvements and cleanups in Liam Howlett's series "VMA tree type safety and remove __vma_adjust()". - Suren Baghdasaryan has done some work on the maintainability of our vm_flags handling in the series "introduce vm_flags modifier functions". - Some pagemap cleanup and generalization work in Mike Rapoport's series "mm, arch: add generic implementation of pfn_valid() for FLATMEM" and "fixups for generic implementation of pfn_valid()" - Baoquan He has done some work to make /proc/vmallocinfo and /proc/kcore better represent the real state of things in his series "mm/vmalloc.c: allow vread() to read out vm_map_ram areas". - Jason Gunthorpe rationalized the GUP system's interface to the rest of the kernel in the series "Simplify the external interface for GUP". - SeongJae Park wishes to migrate people from DAMON's debugfs interface over to its sysfs interface. To support this, we'll temporarily be printing warnings when people use the debugfs interface. See the series "mm/damon: deprecate DAMON debugfs interface". - Andrey Konovalov provided the accurately named "lib/stackdepot: fixes and clean-ups" series. - Huang Ying has provided a dramatic reduction in migration's TLB flush IPI rates with the series "migrate_pages(): batch TLB flushing". - Arnd Bergmann has some objtool fixups in "objtool warning fixes". -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQTTMBEPP41GrTpTJgfdBJ7gKXxAjgUCY/PoPQAKCRDdBJ7gKXxA jlvpAPsFECUBBl20qSue2zCYWnHC7Yk4q9ytTkPB/MMDrFEN9wD/SNKEm2UoK6/K DmxHkn0LAitGgJRS/W9w81yrgig9tAQ= =MlGs -----END PGP SIGNATURE----- Merge tag 'mm-stable-2023-02-20-13-37' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull MM updates from Andrew Morton: - Daniel Verkamp has contributed a memfd series ("mm/memfd: add F_SEAL_EXEC") which permits the setting of the memfd execute bit at memfd creation time, with the option of sealing the state of the X bit. - Peter Xu adds a patch series ("mm/hugetlb: Make huge_pte_offset() thread-safe for pmd unshare") which addresses a rare race condition related to PMD unsharing. - Several folioification patch serieses from Matthew Wilcox, Vishal Moola, Sidhartha Kumar and Lorenzo Stoakes - Johannes Weiner has a series ("mm: push down lock_page_memcg()") which does perform some memcg maintenance and cleanup work. - SeongJae Park has added DAMOS filtering to DAMON, with the series "mm/damon/core: implement damos filter". These filters provide users with finer-grained control over DAMOS's actions. SeongJae has also done some DAMON cleanup work. - Kairui Song adds a series ("Clean up and fixes for swap"). - Vernon Yang contributed the series "Clean up and refinement for maple tree". - Yu Zhao has contributed the "mm: multi-gen LRU: memcg LRU" series. It adds to MGLRU an LRU of memcgs, to improve the scalability of global reclaim. - David Hildenbrand has added some userfaultfd cleanup work in the series "mm: uffd-wp + change_protection() cleanups". - Christoph Hellwig has removed the generic_writepages() library function in the series "remove generic_writepages". - Baolin Wang has performed some maintenance on the compaction code in his series "Some small improvements for compaction". - Sidhartha Kumar is doing some maintenance work on struct page in his series "Get rid of tail page fields". - David Hildenbrand contributed some cleanup, bugfixing and generalization of pte management and of pte debugging in his series "mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on all architectures with swap PTEs". - Mel Gorman and Neil Brown have removed the __GFP_ATOMIC allocation flag in the series "Discard __GFP_ATOMIC". - Sergey Senozhatsky has improved zsmalloc's memory utilization with his series "zsmalloc: make zspage chain size configurable". - Joey Gouly has added prctl() support for prohibiting the creation of writeable+executable mappings. The previous BPF-based approach had shortcomings. See "mm: In-kernel support for memory-deny-write-execute (MDWE)". - Waiman Long did some kmemleak cleanup and bugfixing in the series "mm/kmemleak: Simplify kmemleak_cond_resched() & fix UAF". - T.J. Alumbaugh has contributed some MGLRU cleanup work in his series "mm: multi-gen LRU: improve". - Jiaqi Yan has provided some enhancements to our memory error statistics reporting, mainly by presenting the statistics on a per-node basis. See the series "Introduce per NUMA node memory error statistics". - Mel Gorman has a second and hopefully final shot at fixing a CPU-hog regression in compaction via his series "Fix excessive CPU usage during compaction". - Christoph Hellwig does some vmalloc maintenance work in the series "cleanup vfree and vunmap". - Christoph Hellwig has removed block_device_operations.rw_page() in ths series "remove ->rw_page". - We get some maple_tree improvements and cleanups in Liam Howlett's series "VMA tree type safety and remove __vma_adjust()". - Suren Baghdasaryan has done some work on the maintainability of our vm_flags handling in the series "introduce vm_flags modifier functions". - Some pagemap cleanup and generalization work in Mike Rapoport's series "mm, arch: add generic implementation of pfn_valid() for FLATMEM" and "fixups for generic implementation of pfn_valid()" - Baoquan He has done some work to make /proc/vmallocinfo and /proc/kcore better represent the real state of things in his series "mm/vmalloc.c: allow vread() to read out vm_map_ram areas". - Jason Gunthorpe rationalized the GUP system's interface to the rest of the kernel in the series "Simplify the external interface for GUP". - SeongJae Park wishes to migrate people from DAMON's debugfs interface over to its sysfs interface. To support this, we'll temporarily be printing warnings when people use the debugfs interface. See the series "mm/damon: deprecate DAMON debugfs interface". - Andrey Konovalov provided the accurately named "lib/stackdepot: fixes and clean-ups" series. - Huang Ying has provided a dramatic reduction in migration's TLB flush IPI rates with the series "migrate_pages(): batch TLB flushing". - Arnd Bergmann has some objtool fixups in "objtool warning fixes". * tag 'mm-stable-2023-02-20-13-37' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (505 commits) include/linux/migrate.h: remove unneeded externs mm/memory_hotplug: cleanup return value handing in do_migrate_range() mm/uffd: fix comment in handling pte markers mm: change to return bool for isolate_movable_page() mm: hugetlb: change to return bool for isolate_hugetlb() mm: change to return bool for isolate_lru_page() mm: change to return bool for folio_isolate_lru() objtool: add UACCESS exceptions for __tsan_volatile_read/write kmsan: disable ftrace in kmsan core code kasan: mark addr_has_metadata __always_inline mm: memcontrol: rename memcg_kmem_enabled() sh: initialize max_mapnr m68k/nommu: add missing definition of ARCH_PFN_OFFSET mm: percpu: fix incorrect size in pcpu_obj_full_size() maple_tree: reduce stack usage with gcc-9 and earlier mm: page_alloc: call panic() when memoryless node allocation fails mm: multi-gen LRU: avoid futile retries migrate_pages: move THP/hugetlb migration support check to simplify code migrate_pages: batch flushing TLB migrate_pages: share more code between _unmap and _move ...
3089 lines
80 KiB
C
3089 lines
80 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* linux/fs/buffer.c
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*
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* Copyright (C) 1991, 1992, 2002 Linus Torvalds
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*/
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/*
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* Start bdflush() with kernel_thread not syscall - Paul Gortmaker, 12/95
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*
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* Removed a lot of unnecessary code and simplified things now that
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* the buffer cache isn't our primary cache - Andrew Tridgell 12/96
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*
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* Speed up hash, lru, and free list operations. Use gfp() for allocating
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* hash table, use SLAB cache for buffer heads. SMP threading. -DaveM
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*
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* Added 32k buffer block sizes - these are required older ARM systems. - RMK
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*
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* async buffer flushing, 1999 Andrea Arcangeli <andrea@suse.de>
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*/
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#include <linux/kernel.h>
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#include <linux/sched/signal.h>
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#include <linux/syscalls.h>
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#include <linux/fs.h>
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#include <linux/iomap.h>
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#include <linux/mm.h>
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#include <linux/percpu.h>
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#include <linux/slab.h>
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#include <linux/capability.h>
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#include <linux/blkdev.h>
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#include <linux/file.h>
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#include <linux/quotaops.h>
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#include <linux/highmem.h>
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#include <linux/export.h>
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#include <linux/backing-dev.h>
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#include <linux/writeback.h>
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#include <linux/hash.h>
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#include <linux/suspend.h>
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#include <linux/buffer_head.h>
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#include <linux/task_io_accounting_ops.h>
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#include <linux/bio.h>
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#include <linux/cpu.h>
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#include <linux/bitops.h>
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#include <linux/mpage.h>
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#include <linux/bit_spinlock.h>
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#include <linux/pagevec.h>
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#include <linux/sched/mm.h>
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#include <trace/events/block.h>
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#include <linux/fscrypt.h>
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#include <linux/fsverity.h>
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#include "internal.h"
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static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
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static void submit_bh_wbc(blk_opf_t opf, struct buffer_head *bh,
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struct writeback_control *wbc);
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#define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers)
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inline void touch_buffer(struct buffer_head *bh)
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{
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trace_block_touch_buffer(bh);
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folio_mark_accessed(bh->b_folio);
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}
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EXPORT_SYMBOL(touch_buffer);
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void __lock_buffer(struct buffer_head *bh)
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{
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wait_on_bit_lock_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE);
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}
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EXPORT_SYMBOL(__lock_buffer);
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void unlock_buffer(struct buffer_head *bh)
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{
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clear_bit_unlock(BH_Lock, &bh->b_state);
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smp_mb__after_atomic();
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wake_up_bit(&bh->b_state, BH_Lock);
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}
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EXPORT_SYMBOL(unlock_buffer);
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/*
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* Returns if the folio has dirty or writeback buffers. If all the buffers
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* are unlocked and clean then the folio_test_dirty information is stale. If
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* any of the buffers are locked, it is assumed they are locked for IO.
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*/
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void buffer_check_dirty_writeback(struct folio *folio,
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bool *dirty, bool *writeback)
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{
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struct buffer_head *head, *bh;
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*dirty = false;
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*writeback = false;
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BUG_ON(!folio_test_locked(folio));
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head = folio_buffers(folio);
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if (!head)
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return;
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if (folio_test_writeback(folio))
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*writeback = true;
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bh = head;
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do {
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if (buffer_locked(bh))
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*writeback = true;
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if (buffer_dirty(bh))
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*dirty = true;
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bh = bh->b_this_page;
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} while (bh != head);
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}
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EXPORT_SYMBOL(buffer_check_dirty_writeback);
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/*
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* Block until a buffer comes unlocked. This doesn't stop it
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* from becoming locked again - you have to lock it yourself
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* if you want to preserve its state.
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*/
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void __wait_on_buffer(struct buffer_head * bh)
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{
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wait_on_bit_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE);
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}
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EXPORT_SYMBOL(__wait_on_buffer);
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static void buffer_io_error(struct buffer_head *bh, char *msg)
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{
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if (!test_bit(BH_Quiet, &bh->b_state))
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printk_ratelimited(KERN_ERR
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"Buffer I/O error on dev %pg, logical block %llu%s\n",
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bh->b_bdev, (unsigned long long)bh->b_blocknr, msg);
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}
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/*
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* End-of-IO handler helper function which does not touch the bh after
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* unlocking it.
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* Note: unlock_buffer() sort-of does touch the bh after unlocking it, but
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* a race there is benign: unlock_buffer() only use the bh's address for
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* hashing after unlocking the buffer, so it doesn't actually touch the bh
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* itself.
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*/
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static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate)
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{
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if (uptodate) {
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set_buffer_uptodate(bh);
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} else {
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/* This happens, due to failed read-ahead attempts. */
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clear_buffer_uptodate(bh);
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}
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unlock_buffer(bh);
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}
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/*
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* Default synchronous end-of-IO handler.. Just mark it up-to-date and
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* unlock the buffer.
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*/
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void end_buffer_read_sync(struct buffer_head *bh, int uptodate)
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{
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__end_buffer_read_notouch(bh, uptodate);
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put_bh(bh);
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}
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EXPORT_SYMBOL(end_buffer_read_sync);
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void end_buffer_write_sync(struct buffer_head *bh, int uptodate)
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{
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if (uptodate) {
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set_buffer_uptodate(bh);
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} else {
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buffer_io_error(bh, ", lost sync page write");
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mark_buffer_write_io_error(bh);
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clear_buffer_uptodate(bh);
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}
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unlock_buffer(bh);
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put_bh(bh);
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}
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EXPORT_SYMBOL(end_buffer_write_sync);
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/*
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* Various filesystems appear to want __find_get_block to be non-blocking.
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* But it's the page lock which protects the buffers. To get around this,
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* we get exclusion from try_to_free_buffers with the blockdev mapping's
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* private_lock.
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*
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* Hack idea: for the blockdev mapping, private_lock contention
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* may be quite high. This code could TryLock the page, and if that
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* succeeds, there is no need to take private_lock.
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*/
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static struct buffer_head *
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__find_get_block_slow(struct block_device *bdev, sector_t block)
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{
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struct inode *bd_inode = bdev->bd_inode;
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struct address_space *bd_mapping = bd_inode->i_mapping;
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struct buffer_head *ret = NULL;
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pgoff_t index;
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struct buffer_head *bh;
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struct buffer_head *head;
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struct page *page;
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int all_mapped = 1;
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static DEFINE_RATELIMIT_STATE(last_warned, HZ, 1);
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index = block >> (PAGE_SHIFT - bd_inode->i_blkbits);
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page = find_get_page_flags(bd_mapping, index, FGP_ACCESSED);
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if (!page)
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goto out;
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spin_lock(&bd_mapping->private_lock);
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if (!page_has_buffers(page))
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goto out_unlock;
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head = page_buffers(page);
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bh = head;
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do {
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if (!buffer_mapped(bh))
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all_mapped = 0;
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else if (bh->b_blocknr == block) {
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ret = bh;
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get_bh(bh);
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goto out_unlock;
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}
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bh = bh->b_this_page;
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} while (bh != head);
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/* we might be here because some of the buffers on this page are
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* not mapped. This is due to various races between
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* file io on the block device and getblk. It gets dealt with
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* elsewhere, don't buffer_error if we had some unmapped buffers
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*/
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ratelimit_set_flags(&last_warned, RATELIMIT_MSG_ON_RELEASE);
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if (all_mapped && __ratelimit(&last_warned)) {
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printk("__find_get_block_slow() failed. block=%llu, "
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"b_blocknr=%llu, b_state=0x%08lx, b_size=%zu, "
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"device %pg blocksize: %d\n",
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(unsigned long long)block,
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(unsigned long long)bh->b_blocknr,
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bh->b_state, bh->b_size, bdev,
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1 << bd_inode->i_blkbits);
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}
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out_unlock:
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spin_unlock(&bd_mapping->private_lock);
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put_page(page);
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out:
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return ret;
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}
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static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
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{
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unsigned long flags;
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struct buffer_head *first;
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struct buffer_head *tmp;
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struct folio *folio;
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int folio_uptodate = 1;
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BUG_ON(!buffer_async_read(bh));
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folio = bh->b_folio;
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if (uptodate) {
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set_buffer_uptodate(bh);
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} else {
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clear_buffer_uptodate(bh);
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buffer_io_error(bh, ", async page read");
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folio_set_error(folio);
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}
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|
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/*
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* Be _very_ careful from here on. Bad things can happen if
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* two buffer heads end IO at almost the same time and both
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* decide that the page is now completely done.
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*/
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first = folio_buffers(folio);
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spin_lock_irqsave(&first->b_uptodate_lock, flags);
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clear_buffer_async_read(bh);
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unlock_buffer(bh);
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tmp = bh;
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do {
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if (!buffer_uptodate(tmp))
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folio_uptodate = 0;
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if (buffer_async_read(tmp)) {
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BUG_ON(!buffer_locked(tmp));
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goto still_busy;
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}
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tmp = tmp->b_this_page;
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} while (tmp != bh);
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spin_unlock_irqrestore(&first->b_uptodate_lock, flags);
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|
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/*
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* If all of the buffers are uptodate then we can set the page
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* uptodate.
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*/
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if (folio_uptodate)
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folio_mark_uptodate(folio);
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folio_unlock(folio);
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return;
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still_busy:
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spin_unlock_irqrestore(&first->b_uptodate_lock, flags);
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return;
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}
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|
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struct postprocess_bh_ctx {
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struct work_struct work;
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struct buffer_head *bh;
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};
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|
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static void verify_bh(struct work_struct *work)
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{
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struct postprocess_bh_ctx *ctx =
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container_of(work, struct postprocess_bh_ctx, work);
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struct buffer_head *bh = ctx->bh;
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bool valid;
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valid = fsverity_verify_blocks(page_folio(bh->b_page), bh->b_size,
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bh_offset(bh));
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end_buffer_async_read(bh, valid);
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kfree(ctx);
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}
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|
|
|
static bool need_fsverity(struct buffer_head *bh)
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{
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struct page *page = bh->b_page;
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struct inode *inode = page->mapping->host;
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return fsverity_active(inode) &&
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/* needed by ext4 */
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page->index < DIV_ROUND_UP(inode->i_size, PAGE_SIZE);
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}
|
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|
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static void decrypt_bh(struct work_struct *work)
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{
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struct postprocess_bh_ctx *ctx =
|
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container_of(work, struct postprocess_bh_ctx, work);
|
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struct buffer_head *bh = ctx->bh;
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int err;
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err = fscrypt_decrypt_pagecache_blocks(page_folio(bh->b_page),
|
|
bh->b_size, bh_offset(bh));
|
|
if (err == 0 && need_fsverity(bh)) {
|
|
/*
|
|
* We use different work queues for decryption and for verity
|
|
* because verity may require reading metadata pages that need
|
|
* decryption, and we shouldn't recurse to the same workqueue.
|
|
*/
|
|
INIT_WORK(&ctx->work, verify_bh);
|
|
fsverity_enqueue_verify_work(&ctx->work);
|
|
return;
|
|
}
|
|
end_buffer_async_read(bh, err == 0);
|
|
kfree(ctx);
|
|
}
|
|
|
|
/*
|
|
* I/O completion handler for block_read_full_folio() - pages
|
|
* which come unlocked at the end of I/O.
|
|
*/
|
|
static void end_buffer_async_read_io(struct buffer_head *bh, int uptodate)
|
|
{
|
|
struct inode *inode = bh->b_folio->mapping->host;
|
|
bool decrypt = fscrypt_inode_uses_fs_layer_crypto(inode);
|
|
bool verify = need_fsverity(bh);
|
|
|
|
/* Decrypt (with fscrypt) and/or verify (with fsverity) if needed. */
|
|
if (uptodate && (decrypt || verify)) {
|
|
struct postprocess_bh_ctx *ctx =
|
|
kmalloc(sizeof(*ctx), GFP_ATOMIC);
|
|
|
|
if (ctx) {
|
|
ctx->bh = bh;
|
|
if (decrypt) {
|
|
INIT_WORK(&ctx->work, decrypt_bh);
|
|
fscrypt_enqueue_decrypt_work(&ctx->work);
|
|
} else {
|
|
INIT_WORK(&ctx->work, verify_bh);
|
|
fsverity_enqueue_verify_work(&ctx->work);
|
|
}
|
|
return;
|
|
}
|
|
uptodate = 0;
|
|
}
|
|
end_buffer_async_read(bh, uptodate);
|
|
}
|
|
|
|
/*
|
|
* Completion handler for block_write_full_page() - pages which are unlocked
|
|
* during I/O, and which have PageWriteback cleared upon I/O completion.
|
|
*/
|
|
void end_buffer_async_write(struct buffer_head *bh, int uptodate)
|
|
{
|
|
unsigned long flags;
|
|
struct buffer_head *first;
|
|
struct buffer_head *tmp;
|
|
struct folio *folio;
|
|
|
|
BUG_ON(!buffer_async_write(bh));
|
|
|
|
folio = bh->b_folio;
|
|
if (uptodate) {
|
|
set_buffer_uptodate(bh);
|
|
} else {
|
|
buffer_io_error(bh, ", lost async page write");
|
|
mark_buffer_write_io_error(bh);
|
|
clear_buffer_uptodate(bh);
|
|
folio_set_error(folio);
|
|
}
|
|
|
|
first = folio_buffers(folio);
|
|
spin_lock_irqsave(&first->b_uptodate_lock, flags);
|
|
|
|
clear_buffer_async_write(bh);
|
|
unlock_buffer(bh);
|
|
tmp = bh->b_this_page;
|
|
while (tmp != bh) {
|
|
if (buffer_async_write(tmp)) {
|
|
BUG_ON(!buffer_locked(tmp));
|
|
goto still_busy;
|
|
}
|
|
tmp = tmp->b_this_page;
|
|
}
|
|
spin_unlock_irqrestore(&first->b_uptodate_lock, flags);
|
|
folio_end_writeback(folio);
|
|
return;
|
|
|
|
still_busy:
|
|
spin_unlock_irqrestore(&first->b_uptodate_lock, flags);
|
|
return;
|
|
}
|
|
EXPORT_SYMBOL(end_buffer_async_write);
|
|
|
|
/*
|
|
* If a page's buffers are under async readin (end_buffer_async_read
|
|
* completion) then there is a possibility that another thread of
|
|
* control could lock one of the buffers after it has completed
|
|
* but while some of the other buffers have not completed. This
|
|
* locked buffer would confuse end_buffer_async_read() into not unlocking
|
|
* the page. So the absence of BH_Async_Read tells end_buffer_async_read()
|
|
* that this buffer is not under async I/O.
|
|
*
|
|
* The page comes unlocked when it has no locked buffer_async buffers
|
|
* left.
|
|
*
|
|
* PageLocked prevents anyone starting new async I/O reads any of
|
|
* the buffers.
|
|
*
|
|
* PageWriteback is used to prevent simultaneous writeout of the same
|
|
* page.
|
|
*
|
|
* PageLocked prevents anyone from starting writeback of a page which is
|
|
* under read I/O (PageWriteback is only ever set against a locked page).
|
|
*/
|
|
static void mark_buffer_async_read(struct buffer_head *bh)
|
|
{
|
|
bh->b_end_io = end_buffer_async_read_io;
|
|
set_buffer_async_read(bh);
|
|
}
|
|
|
|
static void mark_buffer_async_write_endio(struct buffer_head *bh,
|
|
bh_end_io_t *handler)
|
|
{
|
|
bh->b_end_io = handler;
|
|
set_buffer_async_write(bh);
|
|
}
|
|
|
|
void mark_buffer_async_write(struct buffer_head *bh)
|
|
{
|
|
mark_buffer_async_write_endio(bh, end_buffer_async_write);
|
|
}
|
|
EXPORT_SYMBOL(mark_buffer_async_write);
|
|
|
|
|
|
/*
|
|
* fs/buffer.c contains helper functions for buffer-backed address space's
|
|
* fsync functions. A common requirement for buffer-based filesystems is
|
|
* that certain data from the backing blockdev needs to be written out for
|
|
* a successful fsync(). For example, ext2 indirect blocks need to be
|
|
* written back and waited upon before fsync() returns.
|
|
*
|
|
* The functions mark_buffer_inode_dirty(), fsync_inode_buffers(),
|
|
* inode_has_buffers() and invalidate_inode_buffers() are provided for the
|
|
* management of a list of dependent buffers at ->i_mapping->private_list.
|
|
*
|
|
* Locking is a little subtle: try_to_free_buffers() will remove buffers
|
|
* from their controlling inode's queue when they are being freed. But
|
|
* try_to_free_buffers() will be operating against the *blockdev* mapping
|
|
* at the time, not against the S_ISREG file which depends on those buffers.
|
|
* So the locking for private_list is via the private_lock in the address_space
|
|
* which backs the buffers. Which is different from the address_space
|
|
* against which the buffers are listed. So for a particular address_space,
|
|
* mapping->private_lock does *not* protect mapping->private_list! In fact,
|
|
* mapping->private_list will always be protected by the backing blockdev's
|
|
* ->private_lock.
|
|
*
|
|
* Which introduces a requirement: all buffers on an address_space's
|
|
* ->private_list must be from the same address_space: the blockdev's.
|
|
*
|
|
* address_spaces which do not place buffers at ->private_list via these
|
|
* utility functions are free to use private_lock and private_list for
|
|
* whatever they want. The only requirement is that list_empty(private_list)
|
|
* be true at clear_inode() time.
|
|
*
|
|
* FIXME: clear_inode should not call invalidate_inode_buffers(). The
|
|
* filesystems should do that. invalidate_inode_buffers() should just go
|
|
* BUG_ON(!list_empty).
|
|
*
|
|
* FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should
|
|
* take an address_space, not an inode. And it should be called
|
|
* mark_buffer_dirty_fsync() to clearly define why those buffers are being
|
|
* queued up.
|
|
*
|
|
* FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the
|
|
* list if it is already on a list. Because if the buffer is on a list,
|
|
* it *must* already be on the right one. If not, the filesystem is being
|
|
* silly. This will save a ton of locking. But first we have to ensure
|
|
* that buffers are taken *off* the old inode's list when they are freed
|
|
* (presumably in truncate). That requires careful auditing of all
|
|
* filesystems (do it inside bforget()). It could also be done by bringing
|
|
* b_inode back.
|
|
*/
|
|
|
|
/*
|
|
* The buffer's backing address_space's private_lock must be held
|
|
*/
|
|
static void __remove_assoc_queue(struct buffer_head *bh)
|
|
{
|
|
list_del_init(&bh->b_assoc_buffers);
|
|
WARN_ON(!bh->b_assoc_map);
|
|
bh->b_assoc_map = NULL;
|
|
}
|
|
|
|
int inode_has_buffers(struct inode *inode)
|
|
{
|
|
return !list_empty(&inode->i_data.private_list);
|
|
}
|
|
|
|
/*
|
|
* osync is designed to support O_SYNC io. It waits synchronously for
|
|
* all already-submitted IO to complete, but does not queue any new
|
|
* writes to the disk.
|
|
*
|
|
* To do O_SYNC writes, just queue the buffer writes with write_dirty_buffer
|
|
* as you dirty the buffers, and then use osync_inode_buffers to wait for
|
|
* completion. Any other dirty buffers which are not yet queued for
|
|
* write will not be flushed to disk by the osync.
|
|
*/
|
|
static int osync_buffers_list(spinlock_t *lock, struct list_head *list)
|
|
{
|
|
struct buffer_head *bh;
|
|
struct list_head *p;
|
|
int err = 0;
|
|
|
|
spin_lock(lock);
|
|
repeat:
|
|
list_for_each_prev(p, list) {
|
|
bh = BH_ENTRY(p);
|
|
if (buffer_locked(bh)) {
|
|
get_bh(bh);
|
|
spin_unlock(lock);
|
|
wait_on_buffer(bh);
|
|
if (!buffer_uptodate(bh))
|
|
err = -EIO;
|
|
brelse(bh);
|
|
spin_lock(lock);
|
|
goto repeat;
|
|
}
|
|
}
|
|
spin_unlock(lock);
|
|
return err;
|
|
}
|
|
|
|
void emergency_thaw_bdev(struct super_block *sb)
|
|
{
|
|
while (sb->s_bdev && !thaw_bdev(sb->s_bdev))
|
|
printk(KERN_WARNING "Emergency Thaw on %pg\n", sb->s_bdev);
|
|
}
|
|
|
|
/**
|
|
* sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers
|
|
* @mapping: the mapping which wants those buffers written
|
|
*
|
|
* Starts I/O against the buffers at mapping->private_list, and waits upon
|
|
* that I/O.
|
|
*
|
|
* Basically, this is a convenience function for fsync().
|
|
* @mapping is a file or directory which needs those buffers to be written for
|
|
* a successful fsync().
|
|
*/
|
|
int sync_mapping_buffers(struct address_space *mapping)
|
|
{
|
|
struct address_space *buffer_mapping = mapping->private_data;
|
|
|
|
if (buffer_mapping == NULL || list_empty(&mapping->private_list))
|
|
return 0;
|
|
|
|
return fsync_buffers_list(&buffer_mapping->private_lock,
|
|
&mapping->private_list);
|
|
}
|
|
EXPORT_SYMBOL(sync_mapping_buffers);
|
|
|
|
/*
|
|
* Called when we've recently written block `bblock', and it is known that
|
|
* `bblock' was for a buffer_boundary() buffer. This means that the block at
|
|
* `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's
|
|
* dirty, schedule it for IO. So that indirects merge nicely with their data.
|
|
*/
|
|
void write_boundary_block(struct block_device *bdev,
|
|
sector_t bblock, unsigned blocksize)
|
|
{
|
|
struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize);
|
|
if (bh) {
|
|
if (buffer_dirty(bh))
|
|
write_dirty_buffer(bh, 0);
|
|
put_bh(bh);
|
|
}
|
|
}
|
|
|
|
void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode)
|
|
{
|
|
struct address_space *mapping = inode->i_mapping;
|
|
struct address_space *buffer_mapping = bh->b_folio->mapping;
|
|
|
|
mark_buffer_dirty(bh);
|
|
if (!mapping->private_data) {
|
|
mapping->private_data = buffer_mapping;
|
|
} else {
|
|
BUG_ON(mapping->private_data != buffer_mapping);
|
|
}
|
|
if (!bh->b_assoc_map) {
|
|
spin_lock(&buffer_mapping->private_lock);
|
|
list_move_tail(&bh->b_assoc_buffers,
|
|
&mapping->private_list);
|
|
bh->b_assoc_map = mapping;
|
|
spin_unlock(&buffer_mapping->private_lock);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(mark_buffer_dirty_inode);
|
|
|
|
/*
|
|
* Add a page to the dirty page list.
|
|
*
|
|
* It is a sad fact of life that this function is called from several places
|
|
* deeply under spinlocking. It may not sleep.
|
|
*
|
|
* If the page has buffers, the uptodate buffers are set dirty, to preserve
|
|
* dirty-state coherency between the page and the buffers. It the page does
|
|
* not have buffers then when they are later attached they will all be set
|
|
* dirty.
|
|
*
|
|
* The buffers are dirtied before the page is dirtied. There's a small race
|
|
* window in which a writepage caller may see the page cleanness but not the
|
|
* buffer dirtiness. That's fine. If this code were to set the page dirty
|
|
* before the buffers, a concurrent writepage caller could clear the page dirty
|
|
* bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean
|
|
* page on the dirty page list.
|
|
*
|
|
* We use private_lock to lock against try_to_free_buffers while using the
|
|
* page's buffer list. Also use this to protect against clean buffers being
|
|
* added to the page after it was set dirty.
|
|
*
|
|
* FIXME: may need to call ->reservepage here as well. That's rather up to the
|
|
* address_space though.
|
|
*/
|
|
bool block_dirty_folio(struct address_space *mapping, struct folio *folio)
|
|
{
|
|
struct buffer_head *head;
|
|
bool newly_dirty;
|
|
|
|
spin_lock(&mapping->private_lock);
|
|
head = folio_buffers(folio);
|
|
if (head) {
|
|
struct buffer_head *bh = head;
|
|
|
|
do {
|
|
set_buffer_dirty(bh);
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
}
|
|
/*
|
|
* Lock out page's memcg migration to keep PageDirty
|
|
* synchronized with per-memcg dirty page counters.
|
|
*/
|
|
folio_memcg_lock(folio);
|
|
newly_dirty = !folio_test_set_dirty(folio);
|
|
spin_unlock(&mapping->private_lock);
|
|
|
|
if (newly_dirty)
|
|
__folio_mark_dirty(folio, mapping, 1);
|
|
|
|
folio_memcg_unlock(folio);
|
|
|
|
if (newly_dirty)
|
|
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
|
|
|
|
return newly_dirty;
|
|
}
|
|
EXPORT_SYMBOL(block_dirty_folio);
|
|
|
|
/*
|
|
* Write out and wait upon a list of buffers.
|
|
*
|
|
* We have conflicting pressures: we want to make sure that all
|
|
* initially dirty buffers get waited on, but that any subsequently
|
|
* dirtied buffers don't. After all, we don't want fsync to last
|
|
* forever if somebody is actively writing to the file.
|
|
*
|
|
* Do this in two main stages: first we copy dirty buffers to a
|
|
* temporary inode list, queueing the writes as we go. Then we clean
|
|
* up, waiting for those writes to complete.
|
|
*
|
|
* During this second stage, any subsequent updates to the file may end
|
|
* up refiling the buffer on the original inode's dirty list again, so
|
|
* there is a chance we will end up with a buffer queued for write but
|
|
* not yet completed on that list. So, as a final cleanup we go through
|
|
* the osync code to catch these locked, dirty buffers without requeuing
|
|
* any newly dirty buffers for write.
|
|
*/
|
|
static int fsync_buffers_list(spinlock_t *lock, struct list_head *list)
|
|
{
|
|
struct buffer_head *bh;
|
|
struct list_head tmp;
|
|
struct address_space *mapping;
|
|
int err = 0, err2;
|
|
struct blk_plug plug;
|
|
|
|
INIT_LIST_HEAD(&tmp);
|
|
blk_start_plug(&plug);
|
|
|
|
spin_lock(lock);
|
|
while (!list_empty(list)) {
|
|
bh = BH_ENTRY(list->next);
|
|
mapping = bh->b_assoc_map;
|
|
__remove_assoc_queue(bh);
|
|
/* Avoid race with mark_buffer_dirty_inode() which does
|
|
* a lockless check and we rely on seeing the dirty bit */
|
|
smp_mb();
|
|
if (buffer_dirty(bh) || buffer_locked(bh)) {
|
|
list_add(&bh->b_assoc_buffers, &tmp);
|
|
bh->b_assoc_map = mapping;
|
|
if (buffer_dirty(bh)) {
|
|
get_bh(bh);
|
|
spin_unlock(lock);
|
|
/*
|
|
* Ensure any pending I/O completes so that
|
|
* write_dirty_buffer() actually writes the
|
|
* current contents - it is a noop if I/O is
|
|
* still in flight on potentially older
|
|
* contents.
|
|
*/
|
|
write_dirty_buffer(bh, REQ_SYNC);
|
|
|
|
/*
|
|
* Kick off IO for the previous mapping. Note
|
|
* that we will not run the very last mapping,
|
|
* wait_on_buffer() will do that for us
|
|
* through sync_buffer().
|
|
*/
|
|
brelse(bh);
|
|
spin_lock(lock);
|
|
}
|
|
}
|
|
}
|
|
|
|
spin_unlock(lock);
|
|
blk_finish_plug(&plug);
|
|
spin_lock(lock);
|
|
|
|
while (!list_empty(&tmp)) {
|
|
bh = BH_ENTRY(tmp.prev);
|
|
get_bh(bh);
|
|
mapping = bh->b_assoc_map;
|
|
__remove_assoc_queue(bh);
|
|
/* Avoid race with mark_buffer_dirty_inode() which does
|
|
* a lockless check and we rely on seeing the dirty bit */
|
|
smp_mb();
|
|
if (buffer_dirty(bh)) {
|
|
list_add(&bh->b_assoc_buffers,
|
|
&mapping->private_list);
|
|
bh->b_assoc_map = mapping;
|
|
}
|
|
spin_unlock(lock);
|
|
wait_on_buffer(bh);
|
|
if (!buffer_uptodate(bh))
|
|
err = -EIO;
|
|
brelse(bh);
|
|
spin_lock(lock);
|
|
}
|
|
|
|
spin_unlock(lock);
|
|
err2 = osync_buffers_list(lock, list);
|
|
if (err)
|
|
return err;
|
|
else
|
|
return err2;
|
|
}
|
|
|
|
/*
|
|
* Invalidate any and all dirty buffers on a given inode. We are
|
|
* probably unmounting the fs, but that doesn't mean we have already
|
|
* done a sync(). Just drop the buffers from the inode list.
|
|
*
|
|
* NOTE: we take the inode's blockdev's mapping's private_lock. Which
|
|
* assumes that all the buffers are against the blockdev. Not true
|
|
* for reiserfs.
|
|
*/
|
|
void invalidate_inode_buffers(struct inode *inode)
|
|
{
|
|
if (inode_has_buffers(inode)) {
|
|
struct address_space *mapping = &inode->i_data;
|
|
struct list_head *list = &mapping->private_list;
|
|
struct address_space *buffer_mapping = mapping->private_data;
|
|
|
|
spin_lock(&buffer_mapping->private_lock);
|
|
while (!list_empty(list))
|
|
__remove_assoc_queue(BH_ENTRY(list->next));
|
|
spin_unlock(&buffer_mapping->private_lock);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(invalidate_inode_buffers);
|
|
|
|
/*
|
|
* Remove any clean buffers from the inode's buffer list. This is called
|
|
* when we're trying to free the inode itself. Those buffers can pin it.
|
|
*
|
|
* Returns true if all buffers were removed.
|
|
*/
|
|
int remove_inode_buffers(struct inode *inode)
|
|
{
|
|
int ret = 1;
|
|
|
|
if (inode_has_buffers(inode)) {
|
|
struct address_space *mapping = &inode->i_data;
|
|
struct list_head *list = &mapping->private_list;
|
|
struct address_space *buffer_mapping = mapping->private_data;
|
|
|
|
spin_lock(&buffer_mapping->private_lock);
|
|
while (!list_empty(list)) {
|
|
struct buffer_head *bh = BH_ENTRY(list->next);
|
|
if (buffer_dirty(bh)) {
|
|
ret = 0;
|
|
break;
|
|
}
|
|
__remove_assoc_queue(bh);
|
|
}
|
|
spin_unlock(&buffer_mapping->private_lock);
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Create the appropriate buffers when given a page for data area and
|
|
* the size of each buffer.. Use the bh->b_this_page linked list to
|
|
* follow the buffers created. Return NULL if unable to create more
|
|
* buffers.
|
|
*
|
|
* The retry flag is used to differentiate async IO (paging, swapping)
|
|
* which may not fail from ordinary buffer allocations.
|
|
*/
|
|
struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
|
|
bool retry)
|
|
{
|
|
struct buffer_head *bh, *head;
|
|
gfp_t gfp = GFP_NOFS | __GFP_ACCOUNT;
|
|
long offset;
|
|
struct mem_cgroup *memcg, *old_memcg;
|
|
|
|
if (retry)
|
|
gfp |= __GFP_NOFAIL;
|
|
|
|
/* The page lock pins the memcg */
|
|
memcg = page_memcg(page);
|
|
old_memcg = set_active_memcg(memcg);
|
|
|
|
head = NULL;
|
|
offset = PAGE_SIZE;
|
|
while ((offset -= size) >= 0) {
|
|
bh = alloc_buffer_head(gfp);
|
|
if (!bh)
|
|
goto no_grow;
|
|
|
|
bh->b_this_page = head;
|
|
bh->b_blocknr = -1;
|
|
head = bh;
|
|
|
|
bh->b_size = size;
|
|
|
|
/* Link the buffer to its page */
|
|
set_bh_page(bh, page, offset);
|
|
}
|
|
out:
|
|
set_active_memcg(old_memcg);
|
|
return head;
|
|
/*
|
|
* In case anything failed, we just free everything we got.
|
|
*/
|
|
no_grow:
|
|
if (head) {
|
|
do {
|
|
bh = head;
|
|
head = head->b_this_page;
|
|
free_buffer_head(bh);
|
|
} while (head);
|
|
}
|
|
|
|
goto out;
|
|
}
|
|
EXPORT_SYMBOL_GPL(alloc_page_buffers);
|
|
|
|
static inline void
|
|
link_dev_buffers(struct page *page, struct buffer_head *head)
|
|
{
|
|
struct buffer_head *bh, *tail;
|
|
|
|
bh = head;
|
|
do {
|
|
tail = bh;
|
|
bh = bh->b_this_page;
|
|
} while (bh);
|
|
tail->b_this_page = head;
|
|
attach_page_private(page, head);
|
|
}
|
|
|
|
static sector_t blkdev_max_block(struct block_device *bdev, unsigned int size)
|
|
{
|
|
sector_t retval = ~((sector_t)0);
|
|
loff_t sz = bdev_nr_bytes(bdev);
|
|
|
|
if (sz) {
|
|
unsigned int sizebits = blksize_bits(size);
|
|
retval = (sz >> sizebits);
|
|
}
|
|
return retval;
|
|
}
|
|
|
|
/*
|
|
* Initialise the state of a blockdev page's buffers.
|
|
*/
|
|
static sector_t
|
|
init_page_buffers(struct page *page, struct block_device *bdev,
|
|
sector_t block, int size)
|
|
{
|
|
struct buffer_head *head = page_buffers(page);
|
|
struct buffer_head *bh = head;
|
|
int uptodate = PageUptodate(page);
|
|
sector_t end_block = blkdev_max_block(bdev, size);
|
|
|
|
do {
|
|
if (!buffer_mapped(bh)) {
|
|
bh->b_end_io = NULL;
|
|
bh->b_private = NULL;
|
|
bh->b_bdev = bdev;
|
|
bh->b_blocknr = block;
|
|
if (uptodate)
|
|
set_buffer_uptodate(bh);
|
|
if (block < end_block)
|
|
set_buffer_mapped(bh);
|
|
}
|
|
block++;
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
|
|
/*
|
|
* Caller needs to validate requested block against end of device.
|
|
*/
|
|
return end_block;
|
|
}
|
|
|
|
/*
|
|
* Create the page-cache page that contains the requested block.
|
|
*
|
|
* This is used purely for blockdev mappings.
|
|
*/
|
|
static int
|
|
grow_dev_page(struct block_device *bdev, sector_t block,
|
|
pgoff_t index, int size, int sizebits, gfp_t gfp)
|
|
{
|
|
struct inode *inode = bdev->bd_inode;
|
|
struct page *page;
|
|
struct buffer_head *bh;
|
|
sector_t end_block;
|
|
int ret = 0;
|
|
gfp_t gfp_mask;
|
|
|
|
gfp_mask = mapping_gfp_constraint(inode->i_mapping, ~__GFP_FS) | gfp;
|
|
|
|
/*
|
|
* XXX: __getblk_slow() can not really deal with failure and
|
|
* will endlessly loop on improvised global reclaim. Prefer
|
|
* looping in the allocator rather than here, at least that
|
|
* code knows what it's doing.
|
|
*/
|
|
gfp_mask |= __GFP_NOFAIL;
|
|
|
|
page = find_or_create_page(inode->i_mapping, index, gfp_mask);
|
|
|
|
BUG_ON(!PageLocked(page));
|
|
|
|
if (page_has_buffers(page)) {
|
|
bh = page_buffers(page);
|
|
if (bh->b_size == size) {
|
|
end_block = init_page_buffers(page, bdev,
|
|
(sector_t)index << sizebits,
|
|
size);
|
|
goto done;
|
|
}
|
|
if (!try_to_free_buffers(page_folio(page)))
|
|
goto failed;
|
|
}
|
|
|
|
/*
|
|
* Allocate some buffers for this page
|
|
*/
|
|
bh = alloc_page_buffers(page, size, true);
|
|
|
|
/*
|
|
* Link the page to the buffers and initialise them. Take the
|
|
* lock to be atomic wrt __find_get_block(), which does not
|
|
* run under the page lock.
|
|
*/
|
|
spin_lock(&inode->i_mapping->private_lock);
|
|
link_dev_buffers(page, bh);
|
|
end_block = init_page_buffers(page, bdev, (sector_t)index << sizebits,
|
|
size);
|
|
spin_unlock(&inode->i_mapping->private_lock);
|
|
done:
|
|
ret = (block < end_block) ? 1 : -ENXIO;
|
|
failed:
|
|
unlock_page(page);
|
|
put_page(page);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Create buffers for the specified block device block's page. If
|
|
* that page was dirty, the buffers are set dirty also.
|
|
*/
|
|
static int
|
|
grow_buffers(struct block_device *bdev, sector_t block, int size, gfp_t gfp)
|
|
{
|
|
pgoff_t index;
|
|
int sizebits;
|
|
|
|
sizebits = PAGE_SHIFT - __ffs(size);
|
|
index = block >> sizebits;
|
|
|
|
/*
|
|
* Check for a block which wants to lie outside our maximum possible
|
|
* pagecache index. (this comparison is done using sector_t types).
|
|
*/
|
|
if (unlikely(index != block >> sizebits)) {
|
|
printk(KERN_ERR "%s: requested out-of-range block %llu for "
|
|
"device %pg\n",
|
|
__func__, (unsigned long long)block,
|
|
bdev);
|
|
return -EIO;
|
|
}
|
|
|
|
/* Create a page with the proper size buffers.. */
|
|
return grow_dev_page(bdev, block, index, size, sizebits, gfp);
|
|
}
|
|
|
|
static struct buffer_head *
|
|
__getblk_slow(struct block_device *bdev, sector_t block,
|
|
unsigned size, gfp_t gfp)
|
|
{
|
|
/* Size must be multiple of hard sectorsize */
|
|
if (unlikely(size & (bdev_logical_block_size(bdev)-1) ||
|
|
(size < 512 || size > PAGE_SIZE))) {
|
|
printk(KERN_ERR "getblk(): invalid block size %d requested\n",
|
|
size);
|
|
printk(KERN_ERR "logical block size: %d\n",
|
|
bdev_logical_block_size(bdev));
|
|
|
|
dump_stack();
|
|
return NULL;
|
|
}
|
|
|
|
for (;;) {
|
|
struct buffer_head *bh;
|
|
int ret;
|
|
|
|
bh = __find_get_block(bdev, block, size);
|
|
if (bh)
|
|
return bh;
|
|
|
|
ret = grow_buffers(bdev, block, size, gfp);
|
|
if (ret < 0)
|
|
return NULL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The relationship between dirty buffers and dirty pages:
|
|
*
|
|
* Whenever a page has any dirty buffers, the page's dirty bit is set, and
|
|
* the page is tagged dirty in the page cache.
|
|
*
|
|
* At all times, the dirtiness of the buffers represents the dirtiness of
|
|
* subsections of the page. If the page has buffers, the page dirty bit is
|
|
* merely a hint about the true dirty state.
|
|
*
|
|
* When a page is set dirty in its entirety, all its buffers are marked dirty
|
|
* (if the page has buffers).
|
|
*
|
|
* When a buffer is marked dirty, its page is dirtied, but the page's other
|
|
* buffers are not.
|
|
*
|
|
* Also. When blockdev buffers are explicitly read with bread(), they
|
|
* individually become uptodate. But their backing page remains not
|
|
* uptodate - even if all of its buffers are uptodate. A subsequent
|
|
* block_read_full_folio() against that folio will discover all the uptodate
|
|
* buffers, will set the folio uptodate and will perform no I/O.
|
|
*/
|
|
|
|
/**
|
|
* mark_buffer_dirty - mark a buffer_head as needing writeout
|
|
* @bh: the buffer_head to mark dirty
|
|
*
|
|
* mark_buffer_dirty() will set the dirty bit against the buffer, then set
|
|
* its backing page dirty, then tag the page as dirty in the page cache
|
|
* and then attach the address_space's inode to its superblock's dirty
|
|
* inode list.
|
|
*
|
|
* mark_buffer_dirty() is atomic. It takes bh->b_folio->mapping->private_lock,
|
|
* i_pages lock and mapping->host->i_lock.
|
|
*/
|
|
void mark_buffer_dirty(struct buffer_head *bh)
|
|
{
|
|
WARN_ON_ONCE(!buffer_uptodate(bh));
|
|
|
|
trace_block_dirty_buffer(bh);
|
|
|
|
/*
|
|
* Very *carefully* optimize the it-is-already-dirty case.
|
|
*
|
|
* Don't let the final "is it dirty" escape to before we
|
|
* perhaps modified the buffer.
|
|
*/
|
|
if (buffer_dirty(bh)) {
|
|
smp_mb();
|
|
if (buffer_dirty(bh))
|
|
return;
|
|
}
|
|
|
|
if (!test_set_buffer_dirty(bh)) {
|
|
struct folio *folio = bh->b_folio;
|
|
struct address_space *mapping = NULL;
|
|
|
|
folio_memcg_lock(folio);
|
|
if (!folio_test_set_dirty(folio)) {
|
|
mapping = folio->mapping;
|
|
if (mapping)
|
|
__folio_mark_dirty(folio, mapping, 0);
|
|
}
|
|
folio_memcg_unlock(folio);
|
|
if (mapping)
|
|
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(mark_buffer_dirty);
|
|
|
|
void mark_buffer_write_io_error(struct buffer_head *bh)
|
|
{
|
|
struct super_block *sb;
|
|
|
|
set_buffer_write_io_error(bh);
|
|
/* FIXME: do we need to set this in both places? */
|
|
if (bh->b_folio && bh->b_folio->mapping)
|
|
mapping_set_error(bh->b_folio->mapping, -EIO);
|
|
if (bh->b_assoc_map)
|
|
mapping_set_error(bh->b_assoc_map, -EIO);
|
|
rcu_read_lock();
|
|
sb = READ_ONCE(bh->b_bdev->bd_super);
|
|
if (sb)
|
|
errseq_set(&sb->s_wb_err, -EIO);
|
|
rcu_read_unlock();
|
|
}
|
|
EXPORT_SYMBOL(mark_buffer_write_io_error);
|
|
|
|
/*
|
|
* Decrement a buffer_head's reference count. If all buffers against a page
|
|
* have zero reference count, are clean and unlocked, and if the page is clean
|
|
* and unlocked then try_to_free_buffers() may strip the buffers from the page
|
|
* in preparation for freeing it (sometimes, rarely, buffers are removed from
|
|
* a page but it ends up not being freed, and buffers may later be reattached).
|
|
*/
|
|
void __brelse(struct buffer_head * buf)
|
|
{
|
|
if (atomic_read(&buf->b_count)) {
|
|
put_bh(buf);
|
|
return;
|
|
}
|
|
WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n");
|
|
}
|
|
EXPORT_SYMBOL(__brelse);
|
|
|
|
/*
|
|
* bforget() is like brelse(), except it discards any
|
|
* potentially dirty data.
|
|
*/
|
|
void __bforget(struct buffer_head *bh)
|
|
{
|
|
clear_buffer_dirty(bh);
|
|
if (bh->b_assoc_map) {
|
|
struct address_space *buffer_mapping = bh->b_folio->mapping;
|
|
|
|
spin_lock(&buffer_mapping->private_lock);
|
|
list_del_init(&bh->b_assoc_buffers);
|
|
bh->b_assoc_map = NULL;
|
|
spin_unlock(&buffer_mapping->private_lock);
|
|
}
|
|
__brelse(bh);
|
|
}
|
|
EXPORT_SYMBOL(__bforget);
|
|
|
|
static struct buffer_head *__bread_slow(struct buffer_head *bh)
|
|
{
|
|
lock_buffer(bh);
|
|
if (buffer_uptodate(bh)) {
|
|
unlock_buffer(bh);
|
|
return bh;
|
|
} else {
|
|
get_bh(bh);
|
|
bh->b_end_io = end_buffer_read_sync;
|
|
submit_bh(REQ_OP_READ, bh);
|
|
wait_on_buffer(bh);
|
|
if (buffer_uptodate(bh))
|
|
return bh;
|
|
}
|
|
brelse(bh);
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block().
|
|
* The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their
|
|
* refcount elevated by one when they're in an LRU. A buffer can only appear
|
|
* once in a particular CPU's LRU. A single buffer can be present in multiple
|
|
* CPU's LRUs at the same time.
|
|
*
|
|
* This is a transparent caching front-end to sb_bread(), sb_getblk() and
|
|
* sb_find_get_block().
|
|
*
|
|
* The LRUs themselves only need locking against invalidate_bh_lrus. We use
|
|
* a local interrupt disable for that.
|
|
*/
|
|
|
|
#define BH_LRU_SIZE 16
|
|
|
|
struct bh_lru {
|
|
struct buffer_head *bhs[BH_LRU_SIZE];
|
|
};
|
|
|
|
static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }};
|
|
|
|
#ifdef CONFIG_SMP
|
|
#define bh_lru_lock() local_irq_disable()
|
|
#define bh_lru_unlock() local_irq_enable()
|
|
#else
|
|
#define bh_lru_lock() preempt_disable()
|
|
#define bh_lru_unlock() preempt_enable()
|
|
#endif
|
|
|
|
static inline void check_irqs_on(void)
|
|
{
|
|
#ifdef irqs_disabled
|
|
BUG_ON(irqs_disabled());
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* Install a buffer_head into this cpu's LRU. If not already in the LRU, it is
|
|
* inserted at the front, and the buffer_head at the back if any is evicted.
|
|
* Or, if already in the LRU it is moved to the front.
|
|
*/
|
|
static void bh_lru_install(struct buffer_head *bh)
|
|
{
|
|
struct buffer_head *evictee = bh;
|
|
struct bh_lru *b;
|
|
int i;
|
|
|
|
check_irqs_on();
|
|
bh_lru_lock();
|
|
|
|
/*
|
|
* the refcount of buffer_head in bh_lru prevents dropping the
|
|
* attached page(i.e., try_to_free_buffers) so it could cause
|
|
* failing page migration.
|
|
* Skip putting upcoming bh into bh_lru until migration is done.
|
|
*/
|
|
if (lru_cache_disabled()) {
|
|
bh_lru_unlock();
|
|
return;
|
|
}
|
|
|
|
b = this_cpu_ptr(&bh_lrus);
|
|
for (i = 0; i < BH_LRU_SIZE; i++) {
|
|
swap(evictee, b->bhs[i]);
|
|
if (evictee == bh) {
|
|
bh_lru_unlock();
|
|
return;
|
|
}
|
|
}
|
|
|
|
get_bh(bh);
|
|
bh_lru_unlock();
|
|
brelse(evictee);
|
|
}
|
|
|
|
/*
|
|
* Look up the bh in this cpu's LRU. If it's there, move it to the head.
|
|
*/
|
|
static struct buffer_head *
|
|
lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size)
|
|
{
|
|
struct buffer_head *ret = NULL;
|
|
unsigned int i;
|
|
|
|
check_irqs_on();
|
|
bh_lru_lock();
|
|
for (i = 0; i < BH_LRU_SIZE; i++) {
|
|
struct buffer_head *bh = __this_cpu_read(bh_lrus.bhs[i]);
|
|
|
|
if (bh && bh->b_blocknr == block && bh->b_bdev == bdev &&
|
|
bh->b_size == size) {
|
|
if (i) {
|
|
while (i) {
|
|
__this_cpu_write(bh_lrus.bhs[i],
|
|
__this_cpu_read(bh_lrus.bhs[i - 1]));
|
|
i--;
|
|
}
|
|
__this_cpu_write(bh_lrus.bhs[0], bh);
|
|
}
|
|
get_bh(bh);
|
|
ret = bh;
|
|
break;
|
|
}
|
|
}
|
|
bh_lru_unlock();
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Perform a pagecache lookup for the matching buffer. If it's there, refresh
|
|
* it in the LRU and mark it as accessed. If it is not present then return
|
|
* NULL
|
|
*/
|
|
struct buffer_head *
|
|
__find_get_block(struct block_device *bdev, sector_t block, unsigned size)
|
|
{
|
|
struct buffer_head *bh = lookup_bh_lru(bdev, block, size);
|
|
|
|
if (bh == NULL) {
|
|
/* __find_get_block_slow will mark the page accessed */
|
|
bh = __find_get_block_slow(bdev, block);
|
|
if (bh)
|
|
bh_lru_install(bh);
|
|
} else
|
|
touch_buffer(bh);
|
|
|
|
return bh;
|
|
}
|
|
EXPORT_SYMBOL(__find_get_block);
|
|
|
|
/*
|
|
* __getblk_gfp() will locate (and, if necessary, create) the buffer_head
|
|
* which corresponds to the passed block_device, block and size. The
|
|
* returned buffer has its reference count incremented.
|
|
*
|
|
* __getblk_gfp() will lock up the machine if grow_dev_page's
|
|
* try_to_free_buffers() attempt is failing. FIXME, perhaps?
|
|
*/
|
|
struct buffer_head *
|
|
__getblk_gfp(struct block_device *bdev, sector_t block,
|
|
unsigned size, gfp_t gfp)
|
|
{
|
|
struct buffer_head *bh = __find_get_block(bdev, block, size);
|
|
|
|
might_sleep();
|
|
if (bh == NULL)
|
|
bh = __getblk_slow(bdev, block, size, gfp);
|
|
return bh;
|
|
}
|
|
EXPORT_SYMBOL(__getblk_gfp);
|
|
|
|
/*
|
|
* Do async read-ahead on a buffer..
|
|
*/
|
|
void __breadahead(struct block_device *bdev, sector_t block, unsigned size)
|
|
{
|
|
struct buffer_head *bh = __getblk(bdev, block, size);
|
|
if (likely(bh)) {
|
|
bh_readahead(bh, REQ_RAHEAD);
|
|
brelse(bh);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(__breadahead);
|
|
|
|
/**
|
|
* __bread_gfp() - reads a specified block and returns the bh
|
|
* @bdev: the block_device to read from
|
|
* @block: number of block
|
|
* @size: size (in bytes) to read
|
|
* @gfp: page allocation flag
|
|
*
|
|
* Reads a specified block, and returns buffer head that contains it.
|
|
* The page cache can be allocated from non-movable area
|
|
* not to prevent page migration if you set gfp to zero.
|
|
* It returns NULL if the block was unreadable.
|
|
*/
|
|
struct buffer_head *
|
|
__bread_gfp(struct block_device *bdev, sector_t block,
|
|
unsigned size, gfp_t gfp)
|
|
{
|
|
struct buffer_head *bh = __getblk_gfp(bdev, block, size, gfp);
|
|
|
|
if (likely(bh) && !buffer_uptodate(bh))
|
|
bh = __bread_slow(bh);
|
|
return bh;
|
|
}
|
|
EXPORT_SYMBOL(__bread_gfp);
|
|
|
|
static void __invalidate_bh_lrus(struct bh_lru *b)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < BH_LRU_SIZE; i++) {
|
|
brelse(b->bhs[i]);
|
|
b->bhs[i] = NULL;
|
|
}
|
|
}
|
|
/*
|
|
* invalidate_bh_lrus() is called rarely - but not only at unmount.
|
|
* This doesn't race because it runs in each cpu either in irq
|
|
* or with preempt disabled.
|
|
*/
|
|
static void invalidate_bh_lru(void *arg)
|
|
{
|
|
struct bh_lru *b = &get_cpu_var(bh_lrus);
|
|
|
|
__invalidate_bh_lrus(b);
|
|
put_cpu_var(bh_lrus);
|
|
}
|
|
|
|
bool has_bh_in_lru(int cpu, void *dummy)
|
|
{
|
|
struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu);
|
|
int i;
|
|
|
|
for (i = 0; i < BH_LRU_SIZE; i++) {
|
|
if (b->bhs[i])
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
void invalidate_bh_lrus(void)
|
|
{
|
|
on_each_cpu_cond(has_bh_in_lru, invalidate_bh_lru, NULL, 1);
|
|
}
|
|
EXPORT_SYMBOL_GPL(invalidate_bh_lrus);
|
|
|
|
/*
|
|
* It's called from workqueue context so we need a bh_lru_lock to close
|
|
* the race with preemption/irq.
|
|
*/
|
|
void invalidate_bh_lrus_cpu(void)
|
|
{
|
|
struct bh_lru *b;
|
|
|
|
bh_lru_lock();
|
|
b = this_cpu_ptr(&bh_lrus);
|
|
__invalidate_bh_lrus(b);
|
|
bh_lru_unlock();
|
|
}
|
|
|
|
void set_bh_page(struct buffer_head *bh,
|
|
struct page *page, unsigned long offset)
|
|
{
|
|
bh->b_page = page;
|
|
BUG_ON(offset >= PAGE_SIZE);
|
|
if (PageHighMem(page))
|
|
/*
|
|
* This catches illegal uses and preserves the offset:
|
|
*/
|
|
bh->b_data = (char *)(0 + offset);
|
|
else
|
|
bh->b_data = page_address(page) + offset;
|
|
}
|
|
EXPORT_SYMBOL(set_bh_page);
|
|
|
|
/*
|
|
* Called when truncating a buffer on a page completely.
|
|
*/
|
|
|
|
/* Bits that are cleared during an invalidate */
|
|
#define BUFFER_FLAGS_DISCARD \
|
|
(1 << BH_Mapped | 1 << BH_New | 1 << BH_Req | \
|
|
1 << BH_Delay | 1 << BH_Unwritten)
|
|
|
|
static void discard_buffer(struct buffer_head * bh)
|
|
{
|
|
unsigned long b_state;
|
|
|
|
lock_buffer(bh);
|
|
clear_buffer_dirty(bh);
|
|
bh->b_bdev = NULL;
|
|
b_state = READ_ONCE(bh->b_state);
|
|
do {
|
|
} while (!try_cmpxchg(&bh->b_state, &b_state,
|
|
b_state & ~BUFFER_FLAGS_DISCARD));
|
|
unlock_buffer(bh);
|
|
}
|
|
|
|
/**
|
|
* block_invalidate_folio - Invalidate part or all of a buffer-backed folio.
|
|
* @folio: The folio which is affected.
|
|
* @offset: start of the range to invalidate
|
|
* @length: length of the range to invalidate
|
|
*
|
|
* block_invalidate_folio() is called when all or part of the folio has been
|
|
* invalidated by a truncate operation.
|
|
*
|
|
* block_invalidate_folio() does not have to release all buffers, but it must
|
|
* ensure that no dirty buffer is left outside @offset and that no I/O
|
|
* is underway against any of the blocks which are outside the truncation
|
|
* point. Because the caller is about to free (and possibly reuse) those
|
|
* blocks on-disk.
|
|
*/
|
|
void block_invalidate_folio(struct folio *folio, size_t offset, size_t length)
|
|
{
|
|
struct buffer_head *head, *bh, *next;
|
|
size_t curr_off = 0;
|
|
size_t stop = length + offset;
|
|
|
|
BUG_ON(!folio_test_locked(folio));
|
|
|
|
/*
|
|
* Check for overflow
|
|
*/
|
|
BUG_ON(stop > folio_size(folio) || stop < length);
|
|
|
|
head = folio_buffers(folio);
|
|
if (!head)
|
|
return;
|
|
|
|
bh = head;
|
|
do {
|
|
size_t next_off = curr_off + bh->b_size;
|
|
next = bh->b_this_page;
|
|
|
|
/*
|
|
* Are we still fully in range ?
|
|
*/
|
|
if (next_off > stop)
|
|
goto out;
|
|
|
|
/*
|
|
* is this block fully invalidated?
|
|
*/
|
|
if (offset <= curr_off)
|
|
discard_buffer(bh);
|
|
curr_off = next_off;
|
|
bh = next;
|
|
} while (bh != head);
|
|
|
|
/*
|
|
* We release buffers only if the entire folio is being invalidated.
|
|
* The get_block cached value has been unconditionally invalidated,
|
|
* so real IO is not possible anymore.
|
|
*/
|
|
if (length == folio_size(folio))
|
|
filemap_release_folio(folio, 0);
|
|
out:
|
|
return;
|
|
}
|
|
EXPORT_SYMBOL(block_invalidate_folio);
|
|
|
|
|
|
/*
|
|
* We attach and possibly dirty the buffers atomically wrt
|
|
* block_dirty_folio() via private_lock. try_to_free_buffers
|
|
* is already excluded via the page lock.
|
|
*/
|
|
void create_empty_buffers(struct page *page,
|
|
unsigned long blocksize, unsigned long b_state)
|
|
{
|
|
struct buffer_head *bh, *head, *tail;
|
|
|
|
head = alloc_page_buffers(page, blocksize, true);
|
|
bh = head;
|
|
do {
|
|
bh->b_state |= b_state;
|
|
tail = bh;
|
|
bh = bh->b_this_page;
|
|
} while (bh);
|
|
tail->b_this_page = head;
|
|
|
|
spin_lock(&page->mapping->private_lock);
|
|
if (PageUptodate(page) || PageDirty(page)) {
|
|
bh = head;
|
|
do {
|
|
if (PageDirty(page))
|
|
set_buffer_dirty(bh);
|
|
if (PageUptodate(page))
|
|
set_buffer_uptodate(bh);
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
}
|
|
attach_page_private(page, head);
|
|
spin_unlock(&page->mapping->private_lock);
|
|
}
|
|
EXPORT_SYMBOL(create_empty_buffers);
|
|
|
|
/**
|
|
* clean_bdev_aliases: clean a range of buffers in block device
|
|
* @bdev: Block device to clean buffers in
|
|
* @block: Start of a range of blocks to clean
|
|
* @len: Number of blocks to clean
|
|
*
|
|
* We are taking a range of blocks for data and we don't want writeback of any
|
|
* buffer-cache aliases starting from return from this function and until the
|
|
* moment when something will explicitly mark the buffer dirty (hopefully that
|
|
* will not happen until we will free that block ;-) We don't even need to mark
|
|
* it not-uptodate - nobody can expect anything from a newly allocated buffer
|
|
* anyway. We used to use unmap_buffer() for such invalidation, but that was
|
|
* wrong. We definitely don't want to mark the alias unmapped, for example - it
|
|
* would confuse anyone who might pick it with bread() afterwards...
|
|
*
|
|
* Also.. Note that bforget() doesn't lock the buffer. So there can be
|
|
* writeout I/O going on against recently-freed buffers. We don't wait on that
|
|
* I/O in bforget() - it's more efficient to wait on the I/O only if we really
|
|
* need to. That happens here.
|
|
*/
|
|
void clean_bdev_aliases(struct block_device *bdev, sector_t block, sector_t len)
|
|
{
|
|
struct inode *bd_inode = bdev->bd_inode;
|
|
struct address_space *bd_mapping = bd_inode->i_mapping;
|
|
struct folio_batch fbatch;
|
|
pgoff_t index = block >> (PAGE_SHIFT - bd_inode->i_blkbits);
|
|
pgoff_t end;
|
|
int i, count;
|
|
struct buffer_head *bh;
|
|
struct buffer_head *head;
|
|
|
|
end = (block + len - 1) >> (PAGE_SHIFT - bd_inode->i_blkbits);
|
|
folio_batch_init(&fbatch);
|
|
while (filemap_get_folios(bd_mapping, &index, end, &fbatch)) {
|
|
count = folio_batch_count(&fbatch);
|
|
for (i = 0; i < count; i++) {
|
|
struct folio *folio = fbatch.folios[i];
|
|
|
|
if (!folio_buffers(folio))
|
|
continue;
|
|
/*
|
|
* We use folio lock instead of bd_mapping->private_lock
|
|
* to pin buffers here since we can afford to sleep and
|
|
* it scales better than a global spinlock lock.
|
|
*/
|
|
folio_lock(folio);
|
|
/* Recheck when the folio is locked which pins bhs */
|
|
head = folio_buffers(folio);
|
|
if (!head)
|
|
goto unlock_page;
|
|
bh = head;
|
|
do {
|
|
if (!buffer_mapped(bh) || (bh->b_blocknr < block))
|
|
goto next;
|
|
if (bh->b_blocknr >= block + len)
|
|
break;
|
|
clear_buffer_dirty(bh);
|
|
wait_on_buffer(bh);
|
|
clear_buffer_req(bh);
|
|
next:
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
unlock_page:
|
|
folio_unlock(folio);
|
|
}
|
|
folio_batch_release(&fbatch);
|
|
cond_resched();
|
|
/* End of range already reached? */
|
|
if (index > end || !index)
|
|
break;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(clean_bdev_aliases);
|
|
|
|
/*
|
|
* Size is a power-of-two in the range 512..PAGE_SIZE,
|
|
* and the case we care about most is PAGE_SIZE.
|
|
*
|
|
* So this *could* possibly be written with those
|
|
* constraints in mind (relevant mostly if some
|
|
* architecture has a slow bit-scan instruction)
|
|
*/
|
|
static inline int block_size_bits(unsigned int blocksize)
|
|
{
|
|
return ilog2(blocksize);
|
|
}
|
|
|
|
static struct buffer_head *create_page_buffers(struct page *page, struct inode *inode, unsigned int b_state)
|
|
{
|
|
BUG_ON(!PageLocked(page));
|
|
|
|
if (!page_has_buffers(page))
|
|
create_empty_buffers(page, 1 << READ_ONCE(inode->i_blkbits),
|
|
b_state);
|
|
return page_buffers(page);
|
|
}
|
|
|
|
/*
|
|
* NOTE! All mapped/uptodate combinations are valid:
|
|
*
|
|
* Mapped Uptodate Meaning
|
|
*
|
|
* No No "unknown" - must do get_block()
|
|
* No Yes "hole" - zero-filled
|
|
* Yes No "allocated" - allocated on disk, not read in
|
|
* Yes Yes "valid" - allocated and up-to-date in memory.
|
|
*
|
|
* "Dirty" is valid only with the last case (mapped+uptodate).
|
|
*/
|
|
|
|
/*
|
|
* While block_write_full_page is writing back the dirty buffers under
|
|
* the page lock, whoever dirtied the buffers may decide to clean them
|
|
* again at any time. We handle that by only looking at the buffer
|
|
* state inside lock_buffer().
|
|
*
|
|
* If block_write_full_page() is called for regular writeback
|
|
* (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a
|
|
* locked buffer. This only can happen if someone has written the buffer
|
|
* directly, with submit_bh(). At the address_space level PageWriteback
|
|
* prevents this contention from occurring.
|
|
*
|
|
* If block_write_full_page() is called with wbc->sync_mode ==
|
|
* WB_SYNC_ALL, the writes are posted using REQ_SYNC; this
|
|
* causes the writes to be flagged as synchronous writes.
|
|
*/
|
|
int __block_write_full_page(struct inode *inode, struct page *page,
|
|
get_block_t *get_block, struct writeback_control *wbc,
|
|
bh_end_io_t *handler)
|
|
{
|
|
int err;
|
|
sector_t block;
|
|
sector_t last_block;
|
|
struct buffer_head *bh, *head;
|
|
unsigned int blocksize, bbits;
|
|
int nr_underway = 0;
|
|
blk_opf_t write_flags = wbc_to_write_flags(wbc);
|
|
|
|
head = create_page_buffers(page, inode,
|
|
(1 << BH_Dirty)|(1 << BH_Uptodate));
|
|
|
|
/*
|
|
* Be very careful. We have no exclusion from block_dirty_folio
|
|
* here, and the (potentially unmapped) buffers may become dirty at
|
|
* any time. If a buffer becomes dirty here after we've inspected it
|
|
* then we just miss that fact, and the page stays dirty.
|
|
*
|
|
* Buffers outside i_size may be dirtied by block_dirty_folio;
|
|
* handle that here by just cleaning them.
|
|
*/
|
|
|
|
bh = head;
|
|
blocksize = bh->b_size;
|
|
bbits = block_size_bits(blocksize);
|
|
|
|
block = (sector_t)page->index << (PAGE_SHIFT - bbits);
|
|
last_block = (i_size_read(inode) - 1) >> bbits;
|
|
|
|
/*
|
|
* Get all the dirty buffers mapped to disk addresses and
|
|
* handle any aliases from the underlying blockdev's mapping.
|
|
*/
|
|
do {
|
|
if (block > last_block) {
|
|
/*
|
|
* mapped buffers outside i_size will occur, because
|
|
* this page can be outside i_size when there is a
|
|
* truncate in progress.
|
|
*/
|
|
/*
|
|
* The buffer was zeroed by block_write_full_page()
|
|
*/
|
|
clear_buffer_dirty(bh);
|
|
set_buffer_uptodate(bh);
|
|
} else if ((!buffer_mapped(bh) || buffer_delay(bh)) &&
|
|
buffer_dirty(bh)) {
|
|
WARN_ON(bh->b_size != blocksize);
|
|
err = get_block(inode, block, bh, 1);
|
|
if (err)
|
|
goto recover;
|
|
clear_buffer_delay(bh);
|
|
if (buffer_new(bh)) {
|
|
/* blockdev mappings never come here */
|
|
clear_buffer_new(bh);
|
|
clean_bdev_bh_alias(bh);
|
|
}
|
|
}
|
|
bh = bh->b_this_page;
|
|
block++;
|
|
} while (bh != head);
|
|
|
|
do {
|
|
if (!buffer_mapped(bh))
|
|
continue;
|
|
/*
|
|
* If it's a fully non-blocking write attempt and we cannot
|
|
* lock the buffer then redirty the page. Note that this can
|
|
* potentially cause a busy-wait loop from writeback threads
|
|
* and kswapd activity, but those code paths have their own
|
|
* higher-level throttling.
|
|
*/
|
|
if (wbc->sync_mode != WB_SYNC_NONE) {
|
|
lock_buffer(bh);
|
|
} else if (!trylock_buffer(bh)) {
|
|
redirty_page_for_writepage(wbc, page);
|
|
continue;
|
|
}
|
|
if (test_clear_buffer_dirty(bh)) {
|
|
mark_buffer_async_write_endio(bh, handler);
|
|
} else {
|
|
unlock_buffer(bh);
|
|
}
|
|
} while ((bh = bh->b_this_page) != head);
|
|
|
|
/*
|
|
* The page and its buffers are protected by PageWriteback(), so we can
|
|
* drop the bh refcounts early.
|
|
*/
|
|
BUG_ON(PageWriteback(page));
|
|
set_page_writeback(page);
|
|
|
|
do {
|
|
struct buffer_head *next = bh->b_this_page;
|
|
if (buffer_async_write(bh)) {
|
|
submit_bh_wbc(REQ_OP_WRITE | write_flags, bh, wbc);
|
|
nr_underway++;
|
|
}
|
|
bh = next;
|
|
} while (bh != head);
|
|
unlock_page(page);
|
|
|
|
err = 0;
|
|
done:
|
|
if (nr_underway == 0) {
|
|
/*
|
|
* The page was marked dirty, but the buffers were
|
|
* clean. Someone wrote them back by hand with
|
|
* write_dirty_buffer/submit_bh. A rare case.
|
|
*/
|
|
end_page_writeback(page);
|
|
|
|
/*
|
|
* The page and buffer_heads can be released at any time from
|
|
* here on.
|
|
*/
|
|
}
|
|
return err;
|
|
|
|
recover:
|
|
/*
|
|
* ENOSPC, or some other error. We may already have added some
|
|
* blocks to the file, so we need to write these out to avoid
|
|
* exposing stale data.
|
|
* The page is currently locked and not marked for writeback
|
|
*/
|
|
bh = head;
|
|
/* Recovery: lock and submit the mapped buffers */
|
|
do {
|
|
if (buffer_mapped(bh) && buffer_dirty(bh) &&
|
|
!buffer_delay(bh)) {
|
|
lock_buffer(bh);
|
|
mark_buffer_async_write_endio(bh, handler);
|
|
} else {
|
|
/*
|
|
* The buffer may have been set dirty during
|
|
* attachment to a dirty page.
|
|
*/
|
|
clear_buffer_dirty(bh);
|
|
}
|
|
} while ((bh = bh->b_this_page) != head);
|
|
SetPageError(page);
|
|
BUG_ON(PageWriteback(page));
|
|
mapping_set_error(page->mapping, err);
|
|
set_page_writeback(page);
|
|
do {
|
|
struct buffer_head *next = bh->b_this_page;
|
|
if (buffer_async_write(bh)) {
|
|
clear_buffer_dirty(bh);
|
|
submit_bh_wbc(REQ_OP_WRITE | write_flags, bh, wbc);
|
|
nr_underway++;
|
|
}
|
|
bh = next;
|
|
} while (bh != head);
|
|
unlock_page(page);
|
|
goto done;
|
|
}
|
|
EXPORT_SYMBOL(__block_write_full_page);
|
|
|
|
/*
|
|
* If a page has any new buffers, zero them out here, and mark them uptodate
|
|
* and dirty so they'll be written out (in order to prevent uninitialised
|
|
* block data from leaking). And clear the new bit.
|
|
*/
|
|
void page_zero_new_buffers(struct page *page, unsigned from, unsigned to)
|
|
{
|
|
unsigned int block_start, block_end;
|
|
struct buffer_head *head, *bh;
|
|
|
|
BUG_ON(!PageLocked(page));
|
|
if (!page_has_buffers(page))
|
|
return;
|
|
|
|
bh = head = page_buffers(page);
|
|
block_start = 0;
|
|
do {
|
|
block_end = block_start + bh->b_size;
|
|
|
|
if (buffer_new(bh)) {
|
|
if (block_end > from && block_start < to) {
|
|
if (!PageUptodate(page)) {
|
|
unsigned start, size;
|
|
|
|
start = max(from, block_start);
|
|
size = min(to, block_end) - start;
|
|
|
|
zero_user(page, start, size);
|
|
set_buffer_uptodate(bh);
|
|
}
|
|
|
|
clear_buffer_new(bh);
|
|
mark_buffer_dirty(bh);
|
|
}
|
|
}
|
|
|
|
block_start = block_end;
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
}
|
|
EXPORT_SYMBOL(page_zero_new_buffers);
|
|
|
|
static void
|
|
iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh,
|
|
const struct iomap *iomap)
|
|
{
|
|
loff_t offset = block << inode->i_blkbits;
|
|
|
|
bh->b_bdev = iomap->bdev;
|
|
|
|
/*
|
|
* Block points to offset in file we need to map, iomap contains
|
|
* the offset at which the map starts. If the map ends before the
|
|
* current block, then do not map the buffer and let the caller
|
|
* handle it.
|
|
*/
|
|
BUG_ON(offset >= iomap->offset + iomap->length);
|
|
|
|
switch (iomap->type) {
|
|
case IOMAP_HOLE:
|
|
/*
|
|
* If the buffer is not up to date or beyond the current EOF,
|
|
* we need to mark it as new to ensure sub-block zeroing is
|
|
* executed if necessary.
|
|
*/
|
|
if (!buffer_uptodate(bh) ||
|
|
(offset >= i_size_read(inode)))
|
|
set_buffer_new(bh);
|
|
break;
|
|
case IOMAP_DELALLOC:
|
|
if (!buffer_uptodate(bh) ||
|
|
(offset >= i_size_read(inode)))
|
|
set_buffer_new(bh);
|
|
set_buffer_uptodate(bh);
|
|
set_buffer_mapped(bh);
|
|
set_buffer_delay(bh);
|
|
break;
|
|
case IOMAP_UNWRITTEN:
|
|
/*
|
|
* For unwritten regions, we always need to ensure that regions
|
|
* in the block we are not writing to are zeroed. Mark the
|
|
* buffer as new to ensure this.
|
|
*/
|
|
set_buffer_new(bh);
|
|
set_buffer_unwritten(bh);
|
|
fallthrough;
|
|
case IOMAP_MAPPED:
|
|
if ((iomap->flags & IOMAP_F_NEW) ||
|
|
offset >= i_size_read(inode))
|
|
set_buffer_new(bh);
|
|
bh->b_blocknr = (iomap->addr + offset - iomap->offset) >>
|
|
inode->i_blkbits;
|
|
set_buffer_mapped(bh);
|
|
break;
|
|
}
|
|
}
|
|
|
|
int __block_write_begin_int(struct folio *folio, loff_t pos, unsigned len,
|
|
get_block_t *get_block, const struct iomap *iomap)
|
|
{
|
|
unsigned from = pos & (PAGE_SIZE - 1);
|
|
unsigned to = from + len;
|
|
struct inode *inode = folio->mapping->host;
|
|
unsigned block_start, block_end;
|
|
sector_t block;
|
|
int err = 0;
|
|
unsigned blocksize, bbits;
|
|
struct buffer_head *bh, *head, *wait[2], **wait_bh=wait;
|
|
|
|
BUG_ON(!folio_test_locked(folio));
|
|
BUG_ON(from > PAGE_SIZE);
|
|
BUG_ON(to > PAGE_SIZE);
|
|
BUG_ON(from > to);
|
|
|
|
head = create_page_buffers(&folio->page, inode, 0);
|
|
blocksize = head->b_size;
|
|
bbits = block_size_bits(blocksize);
|
|
|
|
block = (sector_t)folio->index << (PAGE_SHIFT - bbits);
|
|
|
|
for(bh = head, block_start = 0; bh != head || !block_start;
|
|
block++, block_start=block_end, bh = bh->b_this_page) {
|
|
block_end = block_start + blocksize;
|
|
if (block_end <= from || block_start >= to) {
|
|
if (folio_test_uptodate(folio)) {
|
|
if (!buffer_uptodate(bh))
|
|
set_buffer_uptodate(bh);
|
|
}
|
|
continue;
|
|
}
|
|
if (buffer_new(bh))
|
|
clear_buffer_new(bh);
|
|
if (!buffer_mapped(bh)) {
|
|
WARN_ON(bh->b_size != blocksize);
|
|
if (get_block) {
|
|
err = get_block(inode, block, bh, 1);
|
|
if (err)
|
|
break;
|
|
} else {
|
|
iomap_to_bh(inode, block, bh, iomap);
|
|
}
|
|
|
|
if (buffer_new(bh)) {
|
|
clean_bdev_bh_alias(bh);
|
|
if (folio_test_uptodate(folio)) {
|
|
clear_buffer_new(bh);
|
|
set_buffer_uptodate(bh);
|
|
mark_buffer_dirty(bh);
|
|
continue;
|
|
}
|
|
if (block_end > to || block_start < from)
|
|
folio_zero_segments(folio,
|
|
to, block_end,
|
|
block_start, from);
|
|
continue;
|
|
}
|
|
}
|
|
if (folio_test_uptodate(folio)) {
|
|
if (!buffer_uptodate(bh))
|
|
set_buffer_uptodate(bh);
|
|
continue;
|
|
}
|
|
if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
|
|
!buffer_unwritten(bh) &&
|
|
(block_start < from || block_end > to)) {
|
|
bh_read_nowait(bh, 0);
|
|
*wait_bh++=bh;
|
|
}
|
|
}
|
|
/*
|
|
* If we issued read requests - let them complete.
|
|
*/
|
|
while(wait_bh > wait) {
|
|
wait_on_buffer(*--wait_bh);
|
|
if (!buffer_uptodate(*wait_bh))
|
|
err = -EIO;
|
|
}
|
|
if (unlikely(err))
|
|
page_zero_new_buffers(&folio->page, from, to);
|
|
return err;
|
|
}
|
|
|
|
int __block_write_begin(struct page *page, loff_t pos, unsigned len,
|
|
get_block_t *get_block)
|
|
{
|
|
return __block_write_begin_int(page_folio(page), pos, len, get_block,
|
|
NULL);
|
|
}
|
|
EXPORT_SYMBOL(__block_write_begin);
|
|
|
|
static int __block_commit_write(struct inode *inode, struct page *page,
|
|
unsigned from, unsigned to)
|
|
{
|
|
unsigned block_start, block_end;
|
|
int partial = 0;
|
|
unsigned blocksize;
|
|
struct buffer_head *bh, *head;
|
|
|
|
bh = head = page_buffers(page);
|
|
blocksize = bh->b_size;
|
|
|
|
block_start = 0;
|
|
do {
|
|
block_end = block_start + blocksize;
|
|
if (block_end <= from || block_start >= to) {
|
|
if (!buffer_uptodate(bh))
|
|
partial = 1;
|
|
} else {
|
|
set_buffer_uptodate(bh);
|
|
mark_buffer_dirty(bh);
|
|
}
|
|
if (buffer_new(bh))
|
|
clear_buffer_new(bh);
|
|
|
|
block_start = block_end;
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
|
|
/*
|
|
* If this is a partial write which happened to make all buffers
|
|
* uptodate then we can optimize away a bogus read_folio() for
|
|
* the next read(). Here we 'discover' whether the page went
|
|
* uptodate as a result of this (potentially partial) write.
|
|
*/
|
|
if (!partial)
|
|
SetPageUptodate(page);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* block_write_begin takes care of the basic task of block allocation and
|
|
* bringing partial write blocks uptodate first.
|
|
*
|
|
* The filesystem needs to handle block truncation upon failure.
|
|
*/
|
|
int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
|
|
struct page **pagep, get_block_t *get_block)
|
|
{
|
|
pgoff_t index = pos >> PAGE_SHIFT;
|
|
struct page *page;
|
|
int status;
|
|
|
|
page = grab_cache_page_write_begin(mapping, index);
|
|
if (!page)
|
|
return -ENOMEM;
|
|
|
|
status = __block_write_begin(page, pos, len, get_block);
|
|
if (unlikely(status)) {
|
|
unlock_page(page);
|
|
put_page(page);
|
|
page = NULL;
|
|
}
|
|
|
|
*pagep = page;
|
|
return status;
|
|
}
|
|
EXPORT_SYMBOL(block_write_begin);
|
|
|
|
int block_write_end(struct file *file, struct address_space *mapping,
|
|
loff_t pos, unsigned len, unsigned copied,
|
|
struct page *page, void *fsdata)
|
|
{
|
|
struct inode *inode = mapping->host;
|
|
unsigned start;
|
|
|
|
start = pos & (PAGE_SIZE - 1);
|
|
|
|
if (unlikely(copied < len)) {
|
|
/*
|
|
* The buffers that were written will now be uptodate, so
|
|
* we don't have to worry about a read_folio reading them
|
|
* and overwriting a partial write. However if we have
|
|
* encountered a short write and only partially written
|
|
* into a buffer, it will not be marked uptodate, so a
|
|
* read_folio might come in and destroy our partial write.
|
|
*
|
|
* Do the simplest thing, and just treat any short write to a
|
|
* non uptodate page as a zero-length write, and force the
|
|
* caller to redo the whole thing.
|
|
*/
|
|
if (!PageUptodate(page))
|
|
copied = 0;
|
|
|
|
page_zero_new_buffers(page, start+copied, start+len);
|
|
}
|
|
flush_dcache_page(page);
|
|
|
|
/* This could be a short (even 0-length) commit */
|
|
__block_commit_write(inode, page, start, start+copied);
|
|
|
|
return copied;
|
|
}
|
|
EXPORT_SYMBOL(block_write_end);
|
|
|
|
int generic_write_end(struct file *file, struct address_space *mapping,
|
|
loff_t pos, unsigned len, unsigned copied,
|
|
struct page *page, void *fsdata)
|
|
{
|
|
struct inode *inode = mapping->host;
|
|
loff_t old_size = inode->i_size;
|
|
bool i_size_changed = false;
|
|
|
|
copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
|
|
|
|
/*
|
|
* No need to use i_size_read() here, the i_size cannot change under us
|
|
* because we hold i_rwsem.
|
|
*
|
|
* But it's important to update i_size while still holding page lock:
|
|
* page writeout could otherwise come in and zero beyond i_size.
|
|
*/
|
|
if (pos + copied > inode->i_size) {
|
|
i_size_write(inode, pos + copied);
|
|
i_size_changed = true;
|
|
}
|
|
|
|
unlock_page(page);
|
|
put_page(page);
|
|
|
|
if (old_size < pos)
|
|
pagecache_isize_extended(inode, old_size, pos);
|
|
/*
|
|
* Don't mark the inode dirty under page lock. First, it unnecessarily
|
|
* makes the holding time of page lock longer. Second, it forces lock
|
|
* ordering of page lock and transaction start for journaling
|
|
* filesystems.
|
|
*/
|
|
if (i_size_changed)
|
|
mark_inode_dirty(inode);
|
|
return copied;
|
|
}
|
|
EXPORT_SYMBOL(generic_write_end);
|
|
|
|
/*
|
|
* block_is_partially_uptodate checks whether buffers within a folio are
|
|
* uptodate or not.
|
|
*
|
|
* Returns true if all buffers which correspond to the specified part
|
|
* of the folio are uptodate.
|
|
*/
|
|
bool block_is_partially_uptodate(struct folio *folio, size_t from, size_t count)
|
|
{
|
|
unsigned block_start, block_end, blocksize;
|
|
unsigned to;
|
|
struct buffer_head *bh, *head;
|
|
bool ret = true;
|
|
|
|
head = folio_buffers(folio);
|
|
if (!head)
|
|
return false;
|
|
blocksize = head->b_size;
|
|
to = min_t(unsigned, folio_size(folio) - from, count);
|
|
to = from + to;
|
|
if (from < blocksize && to > folio_size(folio) - blocksize)
|
|
return false;
|
|
|
|
bh = head;
|
|
block_start = 0;
|
|
do {
|
|
block_end = block_start + blocksize;
|
|
if (block_end > from && block_start < to) {
|
|
if (!buffer_uptodate(bh)) {
|
|
ret = false;
|
|
break;
|
|
}
|
|
if (block_end >= to)
|
|
break;
|
|
}
|
|
block_start = block_end;
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(block_is_partially_uptodate);
|
|
|
|
/*
|
|
* Generic "read_folio" function for block devices that have the normal
|
|
* get_block functionality. This is most of the block device filesystems.
|
|
* Reads the folio asynchronously --- the unlock_buffer() and
|
|
* set/clear_buffer_uptodate() functions propagate buffer state into the
|
|
* folio once IO has completed.
|
|
*/
|
|
int block_read_full_folio(struct folio *folio, get_block_t *get_block)
|
|
{
|
|
struct inode *inode = folio->mapping->host;
|
|
sector_t iblock, lblock;
|
|
struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
|
|
unsigned int blocksize, bbits;
|
|
int nr, i;
|
|
int fully_mapped = 1;
|
|
bool page_error = false;
|
|
loff_t limit = i_size_read(inode);
|
|
|
|
/* This is needed for ext4. */
|
|
if (IS_ENABLED(CONFIG_FS_VERITY) && IS_VERITY(inode))
|
|
limit = inode->i_sb->s_maxbytes;
|
|
|
|
VM_BUG_ON_FOLIO(folio_test_large(folio), folio);
|
|
|
|
head = create_page_buffers(&folio->page, inode, 0);
|
|
blocksize = head->b_size;
|
|
bbits = block_size_bits(blocksize);
|
|
|
|
iblock = (sector_t)folio->index << (PAGE_SHIFT - bbits);
|
|
lblock = (limit+blocksize-1) >> bbits;
|
|
bh = head;
|
|
nr = 0;
|
|
i = 0;
|
|
|
|
do {
|
|
if (buffer_uptodate(bh))
|
|
continue;
|
|
|
|
if (!buffer_mapped(bh)) {
|
|
int err = 0;
|
|
|
|
fully_mapped = 0;
|
|
if (iblock < lblock) {
|
|
WARN_ON(bh->b_size != blocksize);
|
|
err = get_block(inode, iblock, bh, 0);
|
|
if (err) {
|
|
folio_set_error(folio);
|
|
page_error = true;
|
|
}
|
|
}
|
|
if (!buffer_mapped(bh)) {
|
|
folio_zero_range(folio, i * blocksize,
|
|
blocksize);
|
|
if (!err)
|
|
set_buffer_uptodate(bh);
|
|
continue;
|
|
}
|
|
/*
|
|
* get_block() might have updated the buffer
|
|
* synchronously
|
|
*/
|
|
if (buffer_uptodate(bh))
|
|
continue;
|
|
}
|
|
arr[nr++] = bh;
|
|
} while (i++, iblock++, (bh = bh->b_this_page) != head);
|
|
|
|
if (fully_mapped)
|
|
folio_set_mappedtodisk(folio);
|
|
|
|
if (!nr) {
|
|
/*
|
|
* All buffers are uptodate - we can set the folio uptodate
|
|
* as well. But not if get_block() returned an error.
|
|
*/
|
|
if (!page_error)
|
|
folio_mark_uptodate(folio);
|
|
folio_unlock(folio);
|
|
return 0;
|
|
}
|
|
|
|
/* Stage two: lock the buffers */
|
|
for (i = 0; i < nr; i++) {
|
|
bh = arr[i];
|
|
lock_buffer(bh);
|
|
mark_buffer_async_read(bh);
|
|
}
|
|
|
|
/*
|
|
* Stage 3: start the IO. Check for uptodateness
|
|
* inside the buffer lock in case another process reading
|
|
* the underlying blockdev brought it uptodate (the sct fix).
|
|
*/
|
|
for (i = 0; i < nr; i++) {
|
|
bh = arr[i];
|
|
if (buffer_uptodate(bh))
|
|
end_buffer_async_read(bh, 1);
|
|
else
|
|
submit_bh(REQ_OP_READ, bh);
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(block_read_full_folio);
|
|
|
|
/* utility function for filesystems that need to do work on expanding
|
|
* truncates. Uses filesystem pagecache writes to allow the filesystem to
|
|
* deal with the hole.
|
|
*/
|
|
int generic_cont_expand_simple(struct inode *inode, loff_t size)
|
|
{
|
|
struct address_space *mapping = inode->i_mapping;
|
|
const struct address_space_operations *aops = mapping->a_ops;
|
|
struct page *page;
|
|
void *fsdata = NULL;
|
|
int err;
|
|
|
|
err = inode_newsize_ok(inode, size);
|
|
if (err)
|
|
goto out;
|
|
|
|
err = aops->write_begin(NULL, mapping, size, 0, &page, &fsdata);
|
|
if (err)
|
|
goto out;
|
|
|
|
err = aops->write_end(NULL, mapping, size, 0, 0, page, fsdata);
|
|
BUG_ON(err > 0);
|
|
|
|
out:
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL(generic_cont_expand_simple);
|
|
|
|
static int cont_expand_zero(struct file *file, struct address_space *mapping,
|
|
loff_t pos, loff_t *bytes)
|
|
{
|
|
struct inode *inode = mapping->host;
|
|
const struct address_space_operations *aops = mapping->a_ops;
|
|
unsigned int blocksize = i_blocksize(inode);
|
|
struct page *page;
|
|
void *fsdata = NULL;
|
|
pgoff_t index, curidx;
|
|
loff_t curpos;
|
|
unsigned zerofrom, offset, len;
|
|
int err = 0;
|
|
|
|
index = pos >> PAGE_SHIFT;
|
|
offset = pos & ~PAGE_MASK;
|
|
|
|
while (index > (curidx = (curpos = *bytes)>>PAGE_SHIFT)) {
|
|
zerofrom = curpos & ~PAGE_MASK;
|
|
if (zerofrom & (blocksize-1)) {
|
|
*bytes |= (blocksize-1);
|
|
(*bytes)++;
|
|
}
|
|
len = PAGE_SIZE - zerofrom;
|
|
|
|
err = aops->write_begin(file, mapping, curpos, len,
|
|
&page, &fsdata);
|
|
if (err)
|
|
goto out;
|
|
zero_user(page, zerofrom, len);
|
|
err = aops->write_end(file, mapping, curpos, len, len,
|
|
page, fsdata);
|
|
if (err < 0)
|
|
goto out;
|
|
BUG_ON(err != len);
|
|
err = 0;
|
|
|
|
balance_dirty_pages_ratelimited(mapping);
|
|
|
|
if (fatal_signal_pending(current)) {
|
|
err = -EINTR;
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
/* page covers the boundary, find the boundary offset */
|
|
if (index == curidx) {
|
|
zerofrom = curpos & ~PAGE_MASK;
|
|
/* if we will expand the thing last block will be filled */
|
|
if (offset <= zerofrom) {
|
|
goto out;
|
|
}
|
|
if (zerofrom & (blocksize-1)) {
|
|
*bytes |= (blocksize-1);
|
|
(*bytes)++;
|
|
}
|
|
len = offset - zerofrom;
|
|
|
|
err = aops->write_begin(file, mapping, curpos, len,
|
|
&page, &fsdata);
|
|
if (err)
|
|
goto out;
|
|
zero_user(page, zerofrom, len);
|
|
err = aops->write_end(file, mapping, curpos, len, len,
|
|
page, fsdata);
|
|
if (err < 0)
|
|
goto out;
|
|
BUG_ON(err != len);
|
|
err = 0;
|
|
}
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* For moronic filesystems that do not allow holes in file.
|
|
* We may have to extend the file.
|
|
*/
|
|
int cont_write_begin(struct file *file, struct address_space *mapping,
|
|
loff_t pos, unsigned len,
|
|
struct page **pagep, void **fsdata,
|
|
get_block_t *get_block, loff_t *bytes)
|
|
{
|
|
struct inode *inode = mapping->host;
|
|
unsigned int blocksize = i_blocksize(inode);
|
|
unsigned int zerofrom;
|
|
int err;
|
|
|
|
err = cont_expand_zero(file, mapping, pos, bytes);
|
|
if (err)
|
|
return err;
|
|
|
|
zerofrom = *bytes & ~PAGE_MASK;
|
|
if (pos+len > *bytes && zerofrom & (blocksize-1)) {
|
|
*bytes |= (blocksize-1);
|
|
(*bytes)++;
|
|
}
|
|
|
|
return block_write_begin(mapping, pos, len, pagep, get_block);
|
|
}
|
|
EXPORT_SYMBOL(cont_write_begin);
|
|
|
|
int block_commit_write(struct page *page, unsigned from, unsigned to)
|
|
{
|
|
struct inode *inode = page->mapping->host;
|
|
__block_commit_write(inode,page,from,to);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(block_commit_write);
|
|
|
|
/*
|
|
* block_page_mkwrite() is not allowed to change the file size as it gets
|
|
* called from a page fault handler when a page is first dirtied. Hence we must
|
|
* be careful to check for EOF conditions here. We set the page up correctly
|
|
* for a written page which means we get ENOSPC checking when writing into
|
|
* holes and correct delalloc and unwritten extent mapping on filesystems that
|
|
* support these features.
|
|
*
|
|
* We are not allowed to take the i_mutex here so we have to play games to
|
|
* protect against truncate races as the page could now be beyond EOF. Because
|
|
* truncate writes the inode size before removing pages, once we have the
|
|
* page lock we can determine safely if the page is beyond EOF. If it is not
|
|
* beyond EOF, then the page is guaranteed safe against truncation until we
|
|
* unlock the page.
|
|
*
|
|
* Direct callers of this function should protect against filesystem freezing
|
|
* using sb_start_pagefault() - sb_end_pagefault() functions.
|
|
*/
|
|
int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
|
|
get_block_t get_block)
|
|
{
|
|
struct page *page = vmf->page;
|
|
struct inode *inode = file_inode(vma->vm_file);
|
|
unsigned long end;
|
|
loff_t size;
|
|
int ret;
|
|
|
|
lock_page(page);
|
|
size = i_size_read(inode);
|
|
if ((page->mapping != inode->i_mapping) ||
|
|
(page_offset(page) > size)) {
|
|
/* We overload EFAULT to mean page got truncated */
|
|
ret = -EFAULT;
|
|
goto out_unlock;
|
|
}
|
|
|
|
/* page is wholly or partially inside EOF */
|
|
if (((page->index + 1) << PAGE_SHIFT) > size)
|
|
end = size & ~PAGE_MASK;
|
|
else
|
|
end = PAGE_SIZE;
|
|
|
|
ret = __block_write_begin(page, 0, end, get_block);
|
|
if (!ret)
|
|
ret = block_commit_write(page, 0, end);
|
|
|
|
if (unlikely(ret < 0))
|
|
goto out_unlock;
|
|
set_page_dirty(page);
|
|
wait_for_stable_page(page);
|
|
return 0;
|
|
out_unlock:
|
|
unlock_page(page);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(block_page_mkwrite);
|
|
|
|
int block_truncate_page(struct address_space *mapping,
|
|
loff_t from, get_block_t *get_block)
|
|
{
|
|
pgoff_t index = from >> PAGE_SHIFT;
|
|
unsigned offset = from & (PAGE_SIZE-1);
|
|
unsigned blocksize;
|
|
sector_t iblock;
|
|
unsigned length, pos;
|
|
struct inode *inode = mapping->host;
|
|
struct page *page;
|
|
struct buffer_head *bh;
|
|
int err;
|
|
|
|
blocksize = i_blocksize(inode);
|
|
length = offset & (blocksize - 1);
|
|
|
|
/* Block boundary? Nothing to do */
|
|
if (!length)
|
|
return 0;
|
|
|
|
length = blocksize - length;
|
|
iblock = (sector_t)index << (PAGE_SHIFT - inode->i_blkbits);
|
|
|
|
page = grab_cache_page(mapping, index);
|
|
err = -ENOMEM;
|
|
if (!page)
|
|
goto out;
|
|
|
|
if (!page_has_buffers(page))
|
|
create_empty_buffers(page, blocksize, 0);
|
|
|
|
/* Find the buffer that contains "offset" */
|
|
bh = page_buffers(page);
|
|
pos = blocksize;
|
|
while (offset >= pos) {
|
|
bh = bh->b_this_page;
|
|
iblock++;
|
|
pos += blocksize;
|
|
}
|
|
|
|
err = 0;
|
|
if (!buffer_mapped(bh)) {
|
|
WARN_ON(bh->b_size != blocksize);
|
|
err = get_block(inode, iblock, bh, 0);
|
|
if (err)
|
|
goto unlock;
|
|
/* unmapped? It's a hole - nothing to do */
|
|
if (!buffer_mapped(bh))
|
|
goto unlock;
|
|
}
|
|
|
|
/* Ok, it's mapped. Make sure it's up-to-date */
|
|
if (PageUptodate(page))
|
|
set_buffer_uptodate(bh);
|
|
|
|
if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) {
|
|
err = bh_read(bh, 0);
|
|
/* Uhhuh. Read error. Complain and punt. */
|
|
if (err < 0)
|
|
goto unlock;
|
|
}
|
|
|
|
zero_user(page, offset, length);
|
|
mark_buffer_dirty(bh);
|
|
err = 0;
|
|
|
|
unlock:
|
|
unlock_page(page);
|
|
put_page(page);
|
|
out:
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL(block_truncate_page);
|
|
|
|
/*
|
|
* The generic ->writepage function for buffer-backed address_spaces
|
|
*/
|
|
int block_write_full_page(struct page *page, get_block_t *get_block,
|
|
struct writeback_control *wbc)
|
|
{
|
|
struct inode * const inode = page->mapping->host;
|
|
loff_t i_size = i_size_read(inode);
|
|
const pgoff_t end_index = i_size >> PAGE_SHIFT;
|
|
unsigned offset;
|
|
|
|
/* Is the page fully inside i_size? */
|
|
if (page->index < end_index)
|
|
return __block_write_full_page(inode, page, get_block, wbc,
|
|
end_buffer_async_write);
|
|
|
|
/* Is the page fully outside i_size? (truncate in progress) */
|
|
offset = i_size & (PAGE_SIZE-1);
|
|
if (page->index >= end_index+1 || !offset) {
|
|
unlock_page(page);
|
|
return 0; /* don't care */
|
|
}
|
|
|
|
/*
|
|
* The page straddles i_size. It must be zeroed out on each and every
|
|
* writepage invocation because it may be mmapped. "A file is mapped
|
|
* in multiples of the page size. For a file that is not a multiple of
|
|
* the page size, the remaining memory is zeroed when mapped, and
|
|
* writes to that region are not written out to the file."
|
|
*/
|
|
zero_user_segment(page, offset, PAGE_SIZE);
|
|
return __block_write_full_page(inode, page, get_block, wbc,
|
|
end_buffer_async_write);
|
|
}
|
|
EXPORT_SYMBOL(block_write_full_page);
|
|
|
|
sector_t generic_block_bmap(struct address_space *mapping, sector_t block,
|
|
get_block_t *get_block)
|
|
{
|
|
struct inode *inode = mapping->host;
|
|
struct buffer_head tmp = {
|
|
.b_size = i_blocksize(inode),
|
|
};
|
|
|
|
get_block(inode, block, &tmp, 0);
|
|
return tmp.b_blocknr;
|
|
}
|
|
EXPORT_SYMBOL(generic_block_bmap);
|
|
|
|
static void end_bio_bh_io_sync(struct bio *bio)
|
|
{
|
|
struct buffer_head *bh = bio->bi_private;
|
|
|
|
if (unlikely(bio_flagged(bio, BIO_QUIET)))
|
|
set_bit(BH_Quiet, &bh->b_state);
|
|
|
|
bh->b_end_io(bh, !bio->bi_status);
|
|
bio_put(bio);
|
|
}
|
|
|
|
static void submit_bh_wbc(blk_opf_t opf, struct buffer_head *bh,
|
|
struct writeback_control *wbc)
|
|
{
|
|
const enum req_op op = opf & REQ_OP_MASK;
|
|
struct bio *bio;
|
|
|
|
BUG_ON(!buffer_locked(bh));
|
|
BUG_ON(!buffer_mapped(bh));
|
|
BUG_ON(!bh->b_end_io);
|
|
BUG_ON(buffer_delay(bh));
|
|
BUG_ON(buffer_unwritten(bh));
|
|
|
|
/*
|
|
* Only clear out a write error when rewriting
|
|
*/
|
|
if (test_set_buffer_req(bh) && (op == REQ_OP_WRITE))
|
|
clear_buffer_write_io_error(bh);
|
|
|
|
if (buffer_meta(bh))
|
|
opf |= REQ_META;
|
|
if (buffer_prio(bh))
|
|
opf |= REQ_PRIO;
|
|
|
|
bio = bio_alloc(bh->b_bdev, 1, opf, GFP_NOIO);
|
|
|
|
fscrypt_set_bio_crypt_ctx_bh(bio, bh, GFP_NOIO);
|
|
|
|
bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
|
|
|
|
bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh));
|
|
BUG_ON(bio->bi_iter.bi_size != bh->b_size);
|
|
|
|
bio->bi_end_io = end_bio_bh_io_sync;
|
|
bio->bi_private = bh;
|
|
|
|
/* Take care of bh's that straddle the end of the device */
|
|
guard_bio_eod(bio);
|
|
|
|
if (wbc) {
|
|
wbc_init_bio(wbc, bio);
|
|
wbc_account_cgroup_owner(wbc, bh->b_page, bh->b_size);
|
|
}
|
|
|
|
submit_bio(bio);
|
|
}
|
|
|
|
void submit_bh(blk_opf_t opf, struct buffer_head *bh)
|
|
{
|
|
submit_bh_wbc(opf, bh, NULL);
|
|
}
|
|
EXPORT_SYMBOL(submit_bh);
|
|
|
|
void write_dirty_buffer(struct buffer_head *bh, blk_opf_t op_flags)
|
|
{
|
|
lock_buffer(bh);
|
|
if (!test_clear_buffer_dirty(bh)) {
|
|
unlock_buffer(bh);
|
|
return;
|
|
}
|
|
bh->b_end_io = end_buffer_write_sync;
|
|
get_bh(bh);
|
|
submit_bh(REQ_OP_WRITE | op_flags, bh);
|
|
}
|
|
EXPORT_SYMBOL(write_dirty_buffer);
|
|
|
|
/*
|
|
* For a data-integrity writeout, we need to wait upon any in-progress I/O
|
|
* and then start new I/O and then wait upon it. The caller must have a ref on
|
|
* the buffer_head.
|
|
*/
|
|
int __sync_dirty_buffer(struct buffer_head *bh, blk_opf_t op_flags)
|
|
{
|
|
WARN_ON(atomic_read(&bh->b_count) < 1);
|
|
lock_buffer(bh);
|
|
if (test_clear_buffer_dirty(bh)) {
|
|
/*
|
|
* The bh should be mapped, but it might not be if the
|
|
* device was hot-removed. Not much we can do but fail the I/O.
|
|
*/
|
|
if (!buffer_mapped(bh)) {
|
|
unlock_buffer(bh);
|
|
return -EIO;
|
|
}
|
|
|
|
get_bh(bh);
|
|
bh->b_end_io = end_buffer_write_sync;
|
|
submit_bh(REQ_OP_WRITE | op_flags, bh);
|
|
wait_on_buffer(bh);
|
|
if (!buffer_uptodate(bh))
|
|
return -EIO;
|
|
} else {
|
|
unlock_buffer(bh);
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(__sync_dirty_buffer);
|
|
|
|
int sync_dirty_buffer(struct buffer_head *bh)
|
|
{
|
|
return __sync_dirty_buffer(bh, REQ_SYNC);
|
|
}
|
|
EXPORT_SYMBOL(sync_dirty_buffer);
|
|
|
|
/*
|
|
* try_to_free_buffers() checks if all the buffers on this particular folio
|
|
* are unused, and releases them if so.
|
|
*
|
|
* Exclusion against try_to_free_buffers may be obtained by either
|
|
* locking the folio or by holding its mapping's private_lock.
|
|
*
|
|
* If the folio is dirty but all the buffers are clean then we need to
|
|
* be sure to mark the folio clean as well. This is because the folio
|
|
* may be against a block device, and a later reattachment of buffers
|
|
* to a dirty folio will set *all* buffers dirty. Which would corrupt
|
|
* filesystem data on the same device.
|
|
*
|
|
* The same applies to regular filesystem folios: if all the buffers are
|
|
* clean then we set the folio clean and proceed. To do that, we require
|
|
* total exclusion from block_dirty_folio(). That is obtained with
|
|
* private_lock.
|
|
*
|
|
* try_to_free_buffers() is non-blocking.
|
|
*/
|
|
static inline int buffer_busy(struct buffer_head *bh)
|
|
{
|
|
return atomic_read(&bh->b_count) |
|
|
(bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock)));
|
|
}
|
|
|
|
static bool
|
|
drop_buffers(struct folio *folio, struct buffer_head **buffers_to_free)
|
|
{
|
|
struct buffer_head *head = folio_buffers(folio);
|
|
struct buffer_head *bh;
|
|
|
|
bh = head;
|
|
do {
|
|
if (buffer_busy(bh))
|
|
goto failed;
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
|
|
do {
|
|
struct buffer_head *next = bh->b_this_page;
|
|
|
|
if (bh->b_assoc_map)
|
|
__remove_assoc_queue(bh);
|
|
bh = next;
|
|
} while (bh != head);
|
|
*buffers_to_free = head;
|
|
folio_detach_private(folio);
|
|
return true;
|
|
failed:
|
|
return false;
|
|
}
|
|
|
|
bool try_to_free_buffers(struct folio *folio)
|
|
{
|
|
struct address_space * const mapping = folio->mapping;
|
|
struct buffer_head *buffers_to_free = NULL;
|
|
bool ret = 0;
|
|
|
|
BUG_ON(!folio_test_locked(folio));
|
|
if (folio_test_writeback(folio))
|
|
return false;
|
|
|
|
if (mapping == NULL) { /* can this still happen? */
|
|
ret = drop_buffers(folio, &buffers_to_free);
|
|
goto out;
|
|
}
|
|
|
|
spin_lock(&mapping->private_lock);
|
|
ret = drop_buffers(folio, &buffers_to_free);
|
|
|
|
/*
|
|
* If the filesystem writes its buffers by hand (eg ext3)
|
|
* then we can have clean buffers against a dirty folio. We
|
|
* clean the folio here; otherwise the VM will never notice
|
|
* that the filesystem did any IO at all.
|
|
*
|
|
* Also, during truncate, discard_buffer will have marked all
|
|
* the folio's buffers clean. We discover that here and clean
|
|
* the folio also.
|
|
*
|
|
* private_lock must be held over this entire operation in order
|
|
* to synchronise against block_dirty_folio and prevent the
|
|
* dirty bit from being lost.
|
|
*/
|
|
if (ret)
|
|
folio_cancel_dirty(folio);
|
|
spin_unlock(&mapping->private_lock);
|
|
out:
|
|
if (buffers_to_free) {
|
|
struct buffer_head *bh = buffers_to_free;
|
|
|
|
do {
|
|
struct buffer_head *next = bh->b_this_page;
|
|
free_buffer_head(bh);
|
|
bh = next;
|
|
} while (bh != buffers_to_free);
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(try_to_free_buffers);
|
|
|
|
/*
|
|
* Buffer-head allocation
|
|
*/
|
|
static struct kmem_cache *bh_cachep __read_mostly;
|
|
|
|
/*
|
|
* Once the number of bh's in the machine exceeds this level, we start
|
|
* stripping them in writeback.
|
|
*/
|
|
static unsigned long max_buffer_heads;
|
|
|
|
int buffer_heads_over_limit;
|
|
|
|
struct bh_accounting {
|
|
int nr; /* Number of live bh's */
|
|
int ratelimit; /* Limit cacheline bouncing */
|
|
};
|
|
|
|
static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0};
|
|
|
|
static void recalc_bh_state(void)
|
|
{
|
|
int i;
|
|
int tot = 0;
|
|
|
|
if (__this_cpu_inc_return(bh_accounting.ratelimit) - 1 < 4096)
|
|
return;
|
|
__this_cpu_write(bh_accounting.ratelimit, 0);
|
|
for_each_online_cpu(i)
|
|
tot += per_cpu(bh_accounting, i).nr;
|
|
buffer_heads_over_limit = (tot > max_buffer_heads);
|
|
}
|
|
|
|
struct buffer_head *alloc_buffer_head(gfp_t gfp_flags)
|
|
{
|
|
struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags);
|
|
if (ret) {
|
|
INIT_LIST_HEAD(&ret->b_assoc_buffers);
|
|
spin_lock_init(&ret->b_uptodate_lock);
|
|
preempt_disable();
|
|
__this_cpu_inc(bh_accounting.nr);
|
|
recalc_bh_state();
|
|
preempt_enable();
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(alloc_buffer_head);
|
|
|
|
void free_buffer_head(struct buffer_head *bh)
|
|
{
|
|
BUG_ON(!list_empty(&bh->b_assoc_buffers));
|
|
kmem_cache_free(bh_cachep, bh);
|
|
preempt_disable();
|
|
__this_cpu_dec(bh_accounting.nr);
|
|
recalc_bh_state();
|
|
preempt_enable();
|
|
}
|
|
EXPORT_SYMBOL(free_buffer_head);
|
|
|
|
static int buffer_exit_cpu_dead(unsigned int cpu)
|
|
{
|
|
int i;
|
|
struct bh_lru *b = &per_cpu(bh_lrus, cpu);
|
|
|
|
for (i = 0; i < BH_LRU_SIZE; i++) {
|
|
brelse(b->bhs[i]);
|
|
b->bhs[i] = NULL;
|
|
}
|
|
this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr);
|
|
per_cpu(bh_accounting, cpu).nr = 0;
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* bh_uptodate_or_lock - Test whether the buffer is uptodate
|
|
* @bh: struct buffer_head
|
|
*
|
|
* Return true if the buffer is up-to-date and false,
|
|
* with the buffer locked, if not.
|
|
*/
|
|
int bh_uptodate_or_lock(struct buffer_head *bh)
|
|
{
|
|
if (!buffer_uptodate(bh)) {
|
|
lock_buffer(bh);
|
|
if (!buffer_uptodate(bh))
|
|
return 0;
|
|
unlock_buffer(bh);
|
|
}
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL(bh_uptodate_or_lock);
|
|
|
|
/**
|
|
* __bh_read - Submit read for a locked buffer
|
|
* @bh: struct buffer_head
|
|
* @op_flags: appending REQ_OP_* flags besides REQ_OP_READ
|
|
* @wait: wait until reading finish
|
|
*
|
|
* Returns zero on success or don't wait, and -EIO on error.
|
|
*/
|
|
int __bh_read(struct buffer_head *bh, blk_opf_t op_flags, bool wait)
|
|
{
|
|
int ret = 0;
|
|
|
|
BUG_ON(!buffer_locked(bh));
|
|
|
|
get_bh(bh);
|
|
bh->b_end_io = end_buffer_read_sync;
|
|
submit_bh(REQ_OP_READ | op_flags, bh);
|
|
if (wait) {
|
|
wait_on_buffer(bh);
|
|
if (!buffer_uptodate(bh))
|
|
ret = -EIO;
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(__bh_read);
|
|
|
|
/**
|
|
* __bh_read_batch - Submit read for a batch of unlocked buffers
|
|
* @nr: entry number of the buffer batch
|
|
* @bhs: a batch of struct buffer_head
|
|
* @op_flags: appending REQ_OP_* flags besides REQ_OP_READ
|
|
* @force_lock: force to get a lock on the buffer if set, otherwise drops any
|
|
* buffer that cannot lock.
|
|
*
|
|
* Returns zero on success or don't wait, and -EIO on error.
|
|
*/
|
|
void __bh_read_batch(int nr, struct buffer_head *bhs[],
|
|
blk_opf_t op_flags, bool force_lock)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < nr; i++) {
|
|
struct buffer_head *bh = bhs[i];
|
|
|
|
if (buffer_uptodate(bh))
|
|
continue;
|
|
|
|
if (force_lock)
|
|
lock_buffer(bh);
|
|
else
|
|
if (!trylock_buffer(bh))
|
|
continue;
|
|
|
|
if (buffer_uptodate(bh)) {
|
|
unlock_buffer(bh);
|
|
continue;
|
|
}
|
|
|
|
bh->b_end_io = end_buffer_read_sync;
|
|
get_bh(bh);
|
|
submit_bh(REQ_OP_READ | op_flags, bh);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(__bh_read_batch);
|
|
|
|
void __init buffer_init(void)
|
|
{
|
|
unsigned long nrpages;
|
|
int ret;
|
|
|
|
bh_cachep = kmem_cache_create("buffer_head",
|
|
sizeof(struct buffer_head), 0,
|
|
(SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
|
|
SLAB_MEM_SPREAD),
|
|
NULL);
|
|
|
|
/*
|
|
* Limit the bh occupancy to 10% of ZONE_NORMAL
|
|
*/
|
|
nrpages = (nr_free_buffer_pages() * 10) / 100;
|
|
max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head));
|
|
ret = cpuhp_setup_state_nocalls(CPUHP_FS_BUFF_DEAD, "fs/buffer:dead",
|
|
NULL, buffer_exit_cpu_dead);
|
|
WARN_ON(ret < 0);
|
|
}
|