linux/fs/btrfs
Linus Torvalds 088737f44b Writeback error handling fixes (pile #2)
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Merge tag 'for-linus-v4.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux

Pull Writeback error handling updates from Jeff Layton:
 "This pile represents the bulk of the writeback error handling fixes
  that I have for this cycle. Some of the earlier patches in this pile
  may look trivial but they are prerequisites for later patches in the
  series.

  The aim of this set is to improve how we track and report writeback
  errors to userland. Most applications that care about data integrity
  will periodically call fsync/fdatasync/msync to ensure that their
  writes have made it to the backing store.

  For a very long time, we have tracked writeback errors using two flags
  in the address_space: AS_EIO and AS_ENOSPC. Those flags are set when a
  writeback error occurs (via mapping_set_error) and are cleared as a
  side-effect of filemap_check_errors (as you noted yesterday). This
  model really sucks for userland.

  Only the first task to call fsync (or msync or fdatasync) will see the
  error. Any subsequent task calling fsync on a file will get back 0
  (unless another writeback error occurs in the interim). If I have
  several tasks writing to a file and calling fsync to ensure that their
  writes got stored, then I need to have them coordinate with one
  another. That's difficult enough, but in a world of containerized
  setups that coordination may even not be possible.

  But wait...it gets worse!

  The calls to filemap_check_errors can be buried pretty far down in the
  call stack, and there are internal callers of filemap_write_and_wait
  and the like that also end up clearing those errors. Many of those
  callers ignore the error return from that function or return it to
  userland at nonsensical times (e.g. truncate() or stat()). If I get
  back -EIO on a truncate, there is no reason to think that it was
  because some previous writeback failed, and a subsequent fsync() will
  (incorrectly) return 0.

  This pile aims to do three things:

   1) ensure that when a writeback error occurs that that error will be
      reported to userland on a subsequent fsync/fdatasync/msync call,
      regardless of what internal callers are doing

   2) report writeback errors on all file descriptions that were open at
      the time that the error occurred. This is a user-visible change,
      but I think most applications are written to assume this behavior
      anyway. Those that aren't are unlikely to be hurt by it.

   3) document what filesystems should do when there is a writeback
      error. Today, there is very little consistency between them, and a
      lot of cargo-cult copying. We need to make it very clear what
      filesystems should do in this situation.

  To achieve this, the set adds a new data type (errseq_t) and then
  builds new writeback error tracking infrastructure around that. Once
  all of that is in place, we change the filesystems to use the new
  infrastructure for reporting wb errors to userland.

  Note that this is just the initial foray into cleaning up this mess.
  There is a lot of work remaining here:

   1) convert the rest of the filesystems in a similar fashion. Once the
      initial set is in, then I think most other fs' will be fairly
      simple to convert. Hopefully most of those can in via individual
      filesystem trees.

   2) convert internal waiters on writeback to use errseq_t for
      detecting errors instead of relying on the AS_* flags. I have some
      draft patches for this for ext4, but they are not quite ready for
      prime time yet.

  This was a discussion topic this year at LSF/MM too. If you're
  interested in the gory details, LWN has some good articles about this:

      https://lwn.net/Articles/718734/
      https://lwn.net/Articles/724307/"

* tag 'for-linus-v4.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
  btrfs: minimal conversion to errseq_t writeback error reporting on fsync
  xfs: minimal conversion to errseq_t writeback error reporting
  ext4: use errseq_t based error handling for reporting data writeback errors
  fs: convert __generic_file_fsync to use errseq_t based reporting
  block: convert to errseq_t based writeback error tracking
  dax: set errors in mapping when writeback fails
  Documentation: flesh out the section in vfs.txt on storing and reporting writeback errors
  mm: set both AS_EIO/AS_ENOSPC and errseq_t in mapping_set_error
  fs: new infrastructure for writeback error handling and reporting
  lib: add errseq_t type and infrastructure for handling it
  mm: don't TestClearPageError in __filemap_fdatawait_range
  mm: clear AS_EIO/AS_ENOSPC when writeback initiation fails
  jbd2: don't clear and reset errors after waiting on writeback
  buffer: set errors in mapping at the time that the error occurs
  fs: check for writeback errors after syncing out buffers in generic_file_fsync
  buffer: use mapping_set_error instead of setting the flag
  mm: fix mapping_set_error call in me_pagecache_dirty
2017-07-07 19:38:17 -07:00
..
tests Btrfs: replace tree->mapping with tree->private_data 2017-06-19 18:25:58 +02:00
acl.c btrfs: Don't clear SGID when inheriting ACLs 2017-06-29 20:24:59 +02:00
async-thread.c btrfs: fix crash when tracepoint arguments are freed by wq callbacks 2017-01-09 11:24:50 +01:00
async-thread.h btrfs: limit async_work allocation and worker func duration 2016-12-13 11:01:30 -08:00
backref.c btrfs: use GFP_KERNEL in init_ipath 2017-06-19 18:26:02 +02:00
backref.h
btrfs_inode.h block: switch bios to blk_status_t 2017-06-09 09:27:32 -06:00
check-integrity.c Merge branch 'for-4.13-part1' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux 2017-07-05 16:41:23 -07:00
check-integrity.h btrfs: take an fs_info directly when the root is not used otherwise 2016-12-06 16:06:59 +01:00
compression.c Merge branch 'for-4.13-part1' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux 2017-07-05 16:41:23 -07:00
compression.h Merge branch 'for-4.13-part1' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux 2017-07-05 16:41:23 -07:00
ctree.c btrfs: adjust includes after vmalloc removal 2017-06-19 18:26:02 +02:00
ctree.h Merge branch 'for-4.13-part1' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux 2017-07-05 16:41:23 -07:00
dedupe.h btrfs: expand cow_file_range() to support in-band dedup and subpage-blocksize 2016-07-26 13:52:25 +02:00
delayed-inode.c btrfs: convert btrfs_delayed_item.refs from atomic_t to refcount_t 2017-04-18 14:07:23 +02:00
delayed-inode.h btrfs: convert btrfs_delayed_item.refs from atomic_t to refcount_t 2017-04-18 14:07:23 +02:00
delayed-ref.c Btrfs: return old and new total ref mods when adding delayed refs 2017-06-29 20:17:01 +02:00
delayed-ref.h Btrfs: return old and new total ref mods when adding delayed refs 2017-06-29 20:17:01 +02:00
dev-replace.c btrfs: fix integer overflow in calc_reclaim_items_nr 2017-06-29 20:17:02 +02:00
dev-replace.h btrfs: constify device path passed to relevant helpers 2017-02-28 14:26:07 +01:00
dir-item.c btrfs: fix validation of XATTR_ITEM dir items 2017-06-29 20:06:11 +02:00
disk-io.c Merge branch 'for-4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2017-07-06 08:59:41 -07:00
disk-io.h Merge branch 'for-4.13-part1' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux 2017-07-05 16:41:23 -07:00
export.c btrfs: Check name_len before reading btrfs_get_name 2017-06-21 19:16:04 +02:00
export.h
extent_io.c Merge branch 'for-4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2017-07-06 08:59:41 -07:00
extent_io.h Merge branch 'for-4.13-part1' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux 2017-07-05 16:41:23 -07:00
extent_map.c btrfs: convert extent_map.refs from atomic_t to refcount_t 2017-04-18 14:07:23 +02:00
extent_map.h btrfs: convert extent_map.refs from atomic_t to refcount_t 2017-04-18 14:07:23 +02:00
extent-tree.c btrfs: fix integer overflow in calc_reclaim_items_nr 2017-06-29 20:17:02 +02:00
file-item.c Merge branch 'for-4.13-part1' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux 2017-07-05 16:41:23 -07:00
file.c Writeback error handling fixes (pile #2) 2017-07-07 19:38:17 -07:00
free-space-cache.c btrfs: use clear_page where appropriate 2017-04-18 14:07:26 +02:00
free-space-cache.h btrfs: free-space-cache, clean up unnecessary root arguments 2017-02-17 12:03:56 +01:00
free-space-tree.c Btrfs: use memalloc_nofs and kvzalloc() for free space tree bitmaps 2017-06-19 18:26:01 +02:00
free-space-tree.h
hash.c crypto: Work around deallocated stack frame reference gcc bug on sparc. 2017-06-08 17:36:03 +08:00
hash.h btrfs: advertise which crc32c implementation is being used at module load 2016-06-06 14:08:28 +02:00
inode-item.c btrfs: take an fs_info directly when the root is not used otherwise 2016-12-06 16:06:59 +01:00
inode-map.c btrfs: qgroup: Introduce extent changeset for qgroup reserve functions 2017-06-29 20:17:02 +02:00
inode-map.h Btrfs: Initialize btrfs_root->highest_objectid when loading tree root and subvolume roots 2016-01-15 19:25:02 +01:00
inode.c Merge branch 'for-4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2017-07-06 08:59:41 -07:00
ioctl.c btrfs: fix integer overflow in calc_reclaim_items_nr 2017-06-29 20:17:02 +02:00
Kconfig
locking.c btrfs: cleanup, remove stray return statements 2016-01-07 14:30:52 +01:00
locking.h
lzo.c btrfs: switch to kvmalloc and GFP_KERNEL in lzo/zlib alloc_workspace 2017-06-19 18:26:02 +02:00
Makefile
math.h
ordered-data.c btrfs: fix integer overflow in calc_reclaim_items_nr 2017-06-29 20:17:02 +02:00
ordered-data.h btrfs: fix integer overflow in calc_reclaim_items_nr 2017-06-29 20:17:02 +02:00
orphan.c
print-tree.c Btrfs: let btrfs_print_leaf print more about block group 2017-06-19 18:26:00 +02:00
print-tree.h btrfs: take an fs_info directly when the root is not used otherwise 2016-12-06 16:06:59 +01:00
props.c btrfs: Verify dir_item in iterate_object_props 2017-06-21 19:16:04 +02:00
props.h
qgroup.c btrfs: fix integer overflow in calc_reclaim_items_nr 2017-06-29 20:17:02 +02:00
qgroup.h btrfs: qgroup: Fix qgroup reserved space underflow by only freeing reserved ranges 2017-06-29 20:17:02 +02:00
raid56.c Merge branch 'for-4.13-part1' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux 2017-07-05 16:41:23 -07:00
raid56.h btrfs: take an fs_info directly when the root is not used otherwise 2016-12-06 16:06:59 +01:00
rcu-string.h
reada.c btrfs: remove unused member err from reada_extent 2017-06-19 18:25:59 +02:00
relocation.c btrfs: fix integer overflow in calc_reclaim_items_nr 2017-06-29 20:17:02 +02:00
root-tree.c btrfs: Check name_len before in btrfs_del_root_ref 2017-06-21 19:16:04 +02:00
scrub.c Merge branch 'for-4.13-part1' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux 2017-07-05 16:41:23 -07:00
send.c btrfs: Check name_len before read in iterate_dir_item 2017-06-21 19:16:04 +02:00
send.h Btrfs: use linux/sizes.h to represent constants 2016-01-07 14:38:02 +01:00
struct-funcs.c btrfs: fix string and comment grammatical issues and typos 2016-05-25 22:35:14 +02:00
super.c btrfs: fix integer overflow in calc_reclaim_items_nr 2017-06-29 20:17:02 +02:00
sysfs.c btrfs: Add quota_override knob into sysfs 2017-06-19 18:25:58 +02:00
sysfs.h btrfs: sysfs: introduce helper for syncing bits with sysfs files 2016-01-21 18:50:40 +01:00
transaction.c btrfs: fix integer overflow in calc_reclaim_items_nr 2017-06-29 20:17:02 +02:00
transaction.h btrfs: remove unused qgroup members from btrfs_trans_handle 2017-04-18 14:07:25 +02:00
tree-defrag.c
tree-log.c btrfs: Check name_len in btrfs_check_ref_name_override 2017-06-21 19:16:04 +02:00
tree-log.h btrfs: Make btrfs_del_inode_ref take btrfs_inode 2017-02-14 15:50:54 +01:00
ulist.c btrfs: ulist: rename ulist_fini to ulist_release 2017-02-17 12:03:50 +01:00
ulist.h btrfs: ulist: rename ulist_fini to ulist_release 2017-02-17 12:03:50 +01:00
uuid-tree.c btrfs: return the actual error value from from btrfs_uuid_tree_iterate 2016-12-19 18:08:15 +01:00
volumes.c Merge branch 'for-4.13-part1' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux 2017-07-05 16:41:23 -07:00
volumes.h btrfs: preallocate device flush bio 2017-06-21 19:03:38 +02:00
xattr.c btrfs: Check name_len with boundary in verify dir_item 2017-06-21 19:16:04 +02:00
xattr.h btrfs: Switch to generic xattr handlers 2016-05-17 19:17:09 -04:00
zlib.c btrfs: switch to kvmalloc and GFP_KERNEL in lzo/zlib alloc_workspace 2017-06-19 18:26:02 +02:00