Commit Graph

90 Commits

Author SHA1 Message Date
Christoph Hellwig
0d07e5573f fs: don't clear I_DIRTY_TIME before calling mark_inode_dirty_sync
__mark_inode_dirty already takes care of that, and for the XFS lazytime
implementation we need to know that ->dirty_inode was called because
I_DIRTY_TIME was set.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2018-03-11 20:27:55 -07:00
Linus Torvalds
e2c5923c34 Merge branch 'for-4.15/block' of git://git.kernel.dk/linux-block
Pull core block layer updates from Jens Axboe:
 "This is the main pull request for block storage for 4.15-rc1.

  Nothing out of the ordinary in here, and no API changes or anything
  like that. Just various new features for drivers, core changes, etc.
  In particular, this pull request contains:

   - A patch series from Bart, closing the whole on blk/scsi-mq queue
     quescing.

   - A series from Christoph, building towards hidden gendisks (for
     multipath) and ability to move bio chains around.

   - NVMe
        - Support for native multipath for NVMe (Christoph).
        - Userspace notifications for AENs (Keith).
        - Command side-effects support (Keith).
        - SGL support (Chaitanya Kulkarni)
        - FC fixes and improvements (James Smart)
        - Lots of fixes and tweaks (Various)

   - bcache
        - New maintainer (Michael Lyle)
        - Writeback control improvements (Michael)
        - Various fixes (Coly, Elena, Eric, Liang, et al)

   - lightnvm updates, mostly centered around the pblk interface
     (Javier, Hans, and Rakesh).

   - Removal of unused bio/bvec kmap atomic interfaces (me, Christoph)

   - Writeback series that fix the much discussed hundreds of millions
     of sync-all units. This goes all the way, as discussed previously
     (me).

   - Fix for missing wakeup on writeback timer adjustments (Yafang
     Shao).

   - Fix laptop mode on blk-mq (me).

   - {mq,name} tupple lookup for IO schedulers, allowing us to have
     alias names. This means you can use 'deadline' on both !mq and on
     mq (where it's called mq-deadline). (me).

   - blktrace race fix, oopsing on sg load (me).

   - blk-mq optimizations (me).

   - Obscure waitqueue race fix for kyber (Omar).

   - NBD fixes (Josef).

   - Disable writeback throttling by default on bfq, like we do on cfq
     (Luca Miccio).

   - Series from Ming that enable us to treat flush requests on blk-mq
     like any other request. This is a really nice cleanup.

   - Series from Ming that improves merging on blk-mq with schedulers,
     getting us closer to flipping the switch on scsi-mq again.

   - BFQ updates (Paolo).

   - blk-mq atomic flags memory ordering fixes (Peter Z).

   - Loop cgroup support (Shaohua).

   - Lots of minor fixes from lots of different folks, both for core and
     driver code"

* 'for-4.15/block' of git://git.kernel.dk/linux-block: (294 commits)
  nvme: fix visibility of "uuid" ns attribute
  blk-mq: fixup some comment typos and lengths
  ide: ide-atapi: fix compile error with defining macro DEBUG
  blk-mq: improve tag waiting setup for non-shared tags
  brd: remove unused brd_mutex
  blk-mq: only run the hardware queue if IO is pending
  block: avoid null pointer dereference on null disk
  fs: guard_bio_eod() needs to consider partitions
  xtensa/simdisk: fix compile error
  nvme: expose subsys attribute to sysfs
  nvme: create 'slaves' and 'holders' entries for hidden controllers
  block: create 'slaves' and 'holders' entries for hidden gendisks
  nvme: also expose the namespace identification sysfs files for mpath nodes
  nvme: implement multipath access to nvme subsystems
  nvme: track shared namespaces
  nvme: introduce a nvme_ns_ids structure
  nvme: track subsystems
  block, nvme: Introduce blk_mq_req_flags_t
  block, scsi: Make SCSI quiesce and resume work reliably
  block: Add the QUEUE_FLAG_PREEMPT_ONLY request queue flag
  ...
2017-11-14 15:32:19 -08:00
Greg Kroah-Hartman
b24413180f License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-02 11:10:55 +01:00
Jens Axboe
9ba4b2dfaf fs: kill 'nr_pages' argument from wakeup_flusher_threads()
Everybody is passing in 0 now, let's get rid of the argument.

Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-10-03 08:38:17 -06:00
Linus Torvalds
0f0d12728e Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull mount flag updates from Al Viro:
 "Another chunk of fmount preparations from dhowells; only trivial
  conflicts for that part. It separates MS_... bits (very grotty
  mount(2) ABI) from the struct super_block ->s_flags (kernel-internal,
  only a small subset of MS_... stuff).

  This does *not* convert the filesystems to new constants; only the
  infrastructure is done here. The next step in that series is where the
  conflicts would be; that's the conversion of filesystems. It's purely
  mechanical and it's better done after the merge, so if you could run
  something like

	list=$(for i in MS_RDONLY MS_NOSUID MS_NODEV MS_NOEXEC MS_SYNCHRONOUS MS_MANDLOCK MS_DIRSYNC MS_NOATIME MS_NODIRATIME MS_SILENT MS_POSIXACL MS_KERNMOUNT MS_I_VERSION MS_LAZYTIME; do git grep -l $i fs drivers/staging/lustre drivers/mtd ipc mm include/linux; done|sort|uniq|grep -v '^fs/namespace.c$')

	sed -i -e 's/\<MS_RDONLY\>/SB_RDONLY/g' \
	        -e 's/\<MS_NOSUID\>/SB_NOSUID/g' \
	        -e 's/\<MS_NODEV\>/SB_NODEV/g' \
	        -e 's/\<MS_NOEXEC\>/SB_NOEXEC/g' \
	        -e 's/\<MS_SYNCHRONOUS\>/SB_SYNCHRONOUS/g' \
	        -e 's/\<MS_MANDLOCK\>/SB_MANDLOCK/g' \
	        -e 's/\<MS_DIRSYNC\>/SB_DIRSYNC/g' \
	        -e 's/\<MS_NOATIME\>/SB_NOATIME/g' \
	        -e 's/\<MS_NODIRATIME\>/SB_NODIRATIME/g' \
	        -e 's/\<MS_SILENT\>/SB_SILENT/g' \
	        -e 's/\<MS_POSIXACL\>/SB_POSIXACL/g' \
	        -e 's/\<MS_KERNMOUNT\>/SB_KERNMOUNT/g' \
	        -e 's/\<MS_I_VERSION\>/SB_I_VERSION/g' \
	        -e 's/\<MS_LAZYTIME\>/SB_LAZYTIME/g' \
	        $list

  and commit it with something along the lines of 'convert filesystems
  away from use of MS_... constants' as commit message, it would save a
  quite a bit of headache next cycle"

* 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  VFS: Differentiate mount flags (MS_*) from internal superblock flags
  VFS: Convert sb->s_flags & MS_RDONLY to sb_rdonly(sb)
  vfs: Add sb_rdonly(sb) to query the MS_RDONLY flag on s_flags
2017-09-14 18:54:01 -07:00
Linus Torvalds
d34fc1adf0 Merge branch 'akpm' (patches from Andrew)
Merge updates from Andrew Morton:

 - various misc bits

 - DAX updates

 - OCFS2

 - most of MM

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (119 commits)
  mm,fork: introduce MADV_WIPEONFORK
  x86,mpx: make mpx depend on x86-64 to free up VMA flag
  mm: add /proc/pid/smaps_rollup
  mm: hugetlb: clear target sub-page last when clearing huge page
  mm: oom: let oom_reap_task and exit_mmap run concurrently
  swap: choose swap device according to numa node
  mm: replace TIF_MEMDIE checks by tsk_is_oom_victim
  mm, oom: do not rely on TIF_MEMDIE for memory reserves access
  z3fold: use per-cpu unbuddied lists
  mm, swap: don't use VMA based swap readahead if HDD is used as swap
  mm, swap: add sysfs interface for VMA based swap readahead
  mm, swap: VMA based swap readahead
  mm, swap: fix swap readahead marking
  mm, swap: add swap readahead hit statistics
  mm/vmalloc.c: don't reinvent the wheel but use existing llist API
  mm/vmstat.c: fix wrong comment
  selftests/memfd: add memfd_create hugetlbfs selftest
  mm/shmem: add hugetlbfs support to memfd_create()
  mm, devm_memremap_pages: use multi-order radix for ZONE_DEVICE lookups
  mm/vmalloc.c: halve the number of comparisons performed in pcpu_get_vm_areas()
  ...
2017-09-06 20:49:49 -07:00
Jeff Layton
de23abd151 fs/sync.c: remove unnecessary NULL f_mapping check in sync_file_range
fsync codepath assumes that f_mapping can never be NULL, but
sync_file_range has a check for that.

Remove the one from sync_file_range as I don't see how you'd ever get a
NULL pointer in here.

Link: http://lkml.kernel.org/r/20170525110509.9434-1-jlayton@redhat.com
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-06 17:27:28 -07:00
Jeff Layton
6454568d96 fs: convert sync_file_range to use errseq_t based error-tracking
sync_file_range doesn't call down into the filesystem directly at all.
It only kicks off writeback of pagecache pages and optionally waits
on the result.

Convert sync_file_range to use errseq_t based error tracking, under the
assumption that most users will prefer this behavior when errors occur.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
2017-08-01 08:39:29 -04:00
David Howells
bc98a42c1f VFS: Convert sb->s_flags & MS_RDONLY to sb_rdonly(sb)
Firstly by applying the following with coccinelle's spatch:

	@@ expression SB; @@
	-SB->s_flags & MS_RDONLY
	+sb_rdonly(SB)

to effect the conversion to sb_rdonly(sb), then by applying:

	@@ expression A, SB; @@
	(
	-(!sb_rdonly(SB)) && A
	+!sb_rdonly(SB) && A
	|
	-A != (sb_rdonly(SB))
	+A != sb_rdonly(SB)
	|
	-A == (sb_rdonly(SB))
	+A == sb_rdonly(SB)
	|
	-!(sb_rdonly(SB))
	+!sb_rdonly(SB)
	|
	-A && (sb_rdonly(SB))
	+A && sb_rdonly(SB)
	|
	-A || (sb_rdonly(SB))
	+A || sb_rdonly(SB)
	|
	-(sb_rdonly(SB)) != A
	+sb_rdonly(SB) != A
	|
	-(sb_rdonly(SB)) == A
	+sb_rdonly(SB) == A
	|
	-(sb_rdonly(SB)) && A
	+sb_rdonly(SB) && A
	|
	-(sb_rdonly(SB)) || A
	+sb_rdonly(SB) || A
	)

	@@ expression A, B, SB; @@
	(
	-(sb_rdonly(SB)) ? 1 : 0
	+sb_rdonly(SB)
	|
	-(sb_rdonly(SB)) ? A : B
	+sb_rdonly(SB) ? A : B
	)

to remove left over excess bracketage and finally by applying:

	@@ expression A, SB; @@
	(
	-(A & MS_RDONLY) != sb_rdonly(SB)
	+(bool)(A & MS_RDONLY) != sb_rdonly(SB)
	|
	-(A & MS_RDONLY) == sb_rdonly(SB)
	+(bool)(A & MS_RDONLY) == sb_rdonly(SB)
	)

to make comparisons against the result of sb_rdonly() (which is a bool)
work correctly.

Signed-off-by: David Howells <dhowells@redhat.com>
2017-07-17 08:45:34 +01:00
Jeff Layton
0f41074a65 fs: remove call_fsync helper function
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
2017-07-05 18:44:23 -04:00
Miklos Szeredi
0eb8af4916 vfs: use helper for calling f_op->fsync()
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2017-02-20 16:51:23 +01:00
Kirill A. Shutemov
09cbfeaf1a mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros
PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
ago with promise that one day it will be possible to implement page
cache with bigger chunks than PAGE_SIZE.

This promise never materialized.  And unlikely will.

We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE.  And it's constant source of confusion on whether
PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
especially on the border between fs and mm.

Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.

Let's stop pretending that pages in page cache are special.  They are
not.

The changes are pretty straight-forward:

 - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;

 - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;

 - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};

 - page_cache_get() -> get_page();

 - page_cache_release() -> put_page();

This patch contains automated changes generated with coccinelle using
script below.  For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.

The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.

There are few places in the code where coccinelle didn't reach.  I'll
fix them manually in a separate patch.  Comments and documentation also
will be addressed with the separate patch.

virtual patch

@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E

@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E

@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT

@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE

@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK

@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)

@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)

@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-04 10:41:08 -07:00
Jan Kara
23d0127096 fs/sync.c: make sync_file_range(2) use WB_SYNC_NONE writeback
sync_file_range(2) is documented to issue writeback only for pages that
are not currently being written.  After all the system call has been
created for userspace to be able to issue background writeout and so
waiting for in-flight IO is undesirable there.  However commit
ee53a891f4 ("mm: do_sync_mapping_range integrity fix") switched
do_sync_mapping_range() and thus sync_file_range() to issue writeback in
WB_SYNC_ALL mode since do_sync_mapping_range() was used by other code
relying on WB_SYNC_ALL semantics.

These days do_sync_mapping_range() went away and we can switch
sync_file_range(2) back to issuing WB_SYNC_NONE writeback.  That should
help PostgreSQL avoid large latency spikes when flushing data in the
background.

Andres measured a 20% increase in transactions per second on an SSD disk.

Signed-off-by: Jan Kara <jack@suse.com>
Reported-by: Andres Freund <andres@anarazel.de>
Tested-By: Andres Freund <andres@anarazel.de>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-06 17:50:42 -08:00
Junichi Nomura
aa750fd71c mm/filemap.c: make global sync not clear error status of individual inodes
filemap_fdatawait() is a function to wait for on-going writeback to
complete but also consume and clear error status of the mapping set during
writeback.

The latter functionality is critical for applications to detect writeback
error with system calls like fsync(2)/fdatasync(2).

However filemap_fdatawait() is also used by sync(2) or FIFREEZE ioctl,
which don't check error status of individual mappings.

As a result, fsync() may not be able to detect writeback error if events
happen in the following order:

   Application                    System admin
   ----------------------------------------------------------
   write data on page cache
                                  Run sync command
                                  writeback completes with error
                                  filemap_fdatawait() clears error
   fsync returns success
   (but the data is not on disk)

This patch adds filemap_fdatawait_keep_errors() for call sites where
writeback error is not handled so that they don't clear error status.

Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Tejun Heo <tj@kernel.org>
Cc: Fengguang Wu <fengguang.wu@gmail.com>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Theodore Ts'o
0ae45f63d4 vfs: add support for a lazytime mount option
Add a new mount option which enables a new "lazytime" mode.  This mode
causes atime, mtime, and ctime updates to only be made to the
in-memory version of the inode.  The on-disk times will only get
updated when (a) if the inode needs to be updated for some non-time
related change, (b) if userspace calls fsync(), syncfs() or sync(), or
(c) just before an undeleted inode is evicted from memory.

This is OK according to POSIX because there are no guarantees after a
crash unless userspace explicitly requests via a fsync(2) call.

For workloads which feature a large number of random write to a
preallocated file, the lazytime mount option significantly reduces
writes to the inode table.  The repeated 4k writes to a single block
will result in undesirable stress on flash devices and SMR disk
drives.  Even on conventional HDD's, the repeated writes to the inode
table block will trigger Adjacent Track Interference (ATI) remediation
latencies, which very negatively impact long tail latencies --- which
is a very big deal for web serving tiers (for example).

Google-Bug-Id: 18297052

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-02-05 02:45:00 -05:00
Al Viro
b583043e99 kill f_dentry uses
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-11-19 13:01:25 -05:00
Anton Altaparmakov
10096fb108 Export sync_filesystem() for modular ->remount_fs() use
This patch changes sync_filesystem() to be EXPORT_SYMBOL().

The reason this is needed is that starting with 3.15 kernel, due to
Theodore Ts'o's commit 02b9984d64 ("fs: push sync_filesystem() down to
the file system's remount_fs()"), all file systems that have dirty data
to be written out need to call sync_filesystem() from their
->remount_fs() method when remounting read-only.

As this is now a generically required function rather than an internal
only function it should be EXPORT_SYMBOL() so that all file systems can
call it.

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-09-05 08:16:21 -07:00
Jan Kara
0dc83bd30b Revert "writeback: do not sync data dirtied after sync start"
This reverts commit c4a391b53a. Dave
Chinner <david@fromorbit.com> has reported the commit may cause some
inodes to be left out from sync(2). This is because we can call
redirty_tail() for some inode (which sets i_dirtied_when to current time)
after sync(2) has started or similarly requeue_inode() can set
i_dirtied_when to current time if writeback had to skip some pages. The
real problem is in the functions clobbering i_dirtied_when but fixing
that isn't trivial so revert is a safer choice for now.

CC: stable@vger.kernel.org # >= 3.13
Signed-off-by: Jan Kara <jack@suse.cz>
2014-02-22 02:02:28 +01:00
Al Viro
d311d79de3 fix O_SYNC|O_APPEND syncing the wrong range on write()
It actually goes back to 2004 ([PATCH] Concurrent O_SYNC write support)
when sync_page_range() had been introduced; generic_file_write{,v}() correctly
synced
	pos_after_write - written .. pos_after_write - 1
but generic_file_aio_write() synced
	pos_before_write .. pos_before_write + written - 1
instead.  Which is not the same thing with O_APPEND, obviously.
A couple of years later correct variant had been killed off when
everything switched to use of generic_file_aio_write().

All users of generic_file_aio_write() are affected, and the same bug
has been copied into other instances of ->aio_write().

The fix is trivial; the only subtle point is that generic_write_sync()
ought to be inlined to avoid calculations useless for the majority of
calls.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-02-09 15:18:09 -05:00
Linus Torvalds
5cbb3d216e Merge branch 'akpm' (patches from Andrew Morton)
Merge first patch-bomb from Andrew Morton:
 "Quite a lot of other stuff is banked up awaiting further
  next->mainline merging, but this batch contains:

   - Lots of random misc patches
   - OCFS2
   - Most of MM
   - backlight updates
   - lib/ updates
   - printk updates
   - checkpatch updates
   - epoll tweaking
   - rtc updates
   - hfs
   - hfsplus
   - documentation
   - procfs
   - update gcov to gcc-4.7 format
   - IPC"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (269 commits)
  ipc, msg: fix message length check for negative values
  ipc/util.c: remove unnecessary work pending test
  devpts: plug the memory leak in kill_sb
  ./Makefile: export initial ramdisk compression config option
  init/Kconfig: add option to disable kernel compression
  drivers: w1: make w1_slave::flags long to avoid memory corruption
  drivers/w1/masters/ds1wm.cuse dev_get_platdata()
  drivers/memstick/core/ms_block.c: fix unreachable state in h_msb_read_page()
  drivers/memstick/core/mspro_block.c: fix attributes array allocation
  drivers/pps/clients/pps-gpio.c: remove redundant of_match_ptr
  kernel/panic.c: reduce 1 byte usage for print tainted buffer
  gcov: reuse kbasename helper
  kernel/gcov/fs.c: use pr_warn()
  kernel/module.c: use pr_foo()
  gcov: compile specific gcov implementation based on gcc version
  gcov: add support for gcc 4.7 gcov format
  gcov: move gcov structs definitions to a gcc version specific file
  kernel/taskstats.c: return -ENOMEM when alloc memory fails in add_del_listener()
  kernel/taskstats.c: add nla_nest_cancel() for failure processing between nla_nest_start() and nla_nest_end()
  kernel/sysctl_binary.c: use scnprintf() instead of snprintf()
  ...
2013-11-13 15:45:43 +09:00
Jan Kara
c4a391b53a writeback: do not sync data dirtied after sync start
When there are processes heavily creating small files while sync(2) is
running, it can easily happen that quite some new files are created
between WB_SYNC_NONE and WB_SYNC_ALL pass of sync(2).  That can happen
especially if there are several busy filesystems (remember that sync
traverses filesystems sequentially and waits in WB_SYNC_ALL phase on one
fs before starting it on another fs).  Because WB_SYNC_ALL pass is slow
(e.g.  causes a transaction commit and cache flush for each inode in
ext3), resulting sync(2) times are rather large.

The following script reproduces the problem:

  function run_writers
  {
    for (( i = 0; i < 10; i++ )); do
      mkdir $1/dir$i
      for (( j = 0; j < 40000; j++ )); do
        dd if=/dev/zero of=$1/dir$i/$j bs=4k count=4 &>/dev/null
      done &
    done
  }

  for dir in "$@"; do
    run_writers $dir
  done

  sleep 40
  time sync

Fix the problem by disregarding inodes dirtied after sync(2) was called
in the WB_SYNC_ALL pass.  To allow for this, sync_inodes_sb() now takes
a time stamp when sync has started which is used for setting up work for
flusher threads.

To give some numbers, when above script is run on two ext4 filesystems
on simple SATA drive, the average sync time from 10 runs is 267.549
seconds with standard deviation 104.799426.  With the patched kernel,
the average sync time from 10 runs is 2.995 seconds with standard
deviation 0.096.

Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Fengguang Wu <fengguang.wu@intel.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-11-13 12:09:07 +09:00
Al Viro
72c2d53192 file->f_op is never NULL...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-10-24 23:34:54 -04:00
Al Viro
4a0fd5bf0f teach SYSCALL_DEFINE<n> how to deal with long long/unsigned long long
... and convert a bunch of SYSCALL_DEFINE ones to SYSCALL_DEFINE<n>,
killing the boilerplate crap around them.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-03-03 22:46:22 -05:00
Al Viro
496ad9aa8e new helper: file_inode(file)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-22 23:31:31 -05:00
Al Viro
2903ff019b switch simple cases of fget_light to fdget
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-09-26 22:20:08 -04:00
Jan Kara
4ea425b63a vfs: Avoid unnecessary WB_SYNC_NONE writeback during sys_sync and reorder sync passes
wakeup_flusher_threads(0) will queue work doing complete writeback for each
flusher thread. Thus there is not much point in submitting another work doing
full inode WB_SYNC_NONE writeback by writeback_inodes_sb().

After this change it does not make sense to call nonblocking ->sync_fs and
block device flush before calling sync_inodes_sb() because
wakeup_flusher_threads() is completely asynchronous and thus these functions
would be called in parallel with inode writeback running which will effectively
void any work they do. So we move sync_inodes_sb() call before these two
functions.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-07-22 23:59:01 +04:00
Jan Kara
d0e91b13eb vfs: Remove unnecessary flushing of block devices
It is not necessary to write block devices twice. The reason why we first did
flush and then proper sync is that
  for_each_bdev() {
    write_bdev()
    wait_for_completion()
  }
is much slower than
  for_each_bdev()
    write_bdev()
  for_each_bdev()
    wait_for_completion()
when there is bigger amount of data. But as is seen in the above, there's no real
need to scan pages and submit them twice. We just need to separate the submission
and waiting part. This patch does that.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-07-22 23:58:53 +04:00
Jan Kara
a8c7176b6d vfs: Make sys_sync writeout also block device inodes
In case block device does not have filesystem mounted on it, sys_sync will just
ignore it and doesn't writeout its dirty pages. This is because writeback code
avoids writing inodes from superblock without backing device and
blockdev_superblock is such a superblock.  Since it's unexpected that sync
doesn't writeout dirty data for block devices be nice to users and change the
behavior to do so. So now we iterate over all block devices on blockdev_super
instead of iterating over all superblocks when syncing block devices.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-07-22 23:58:49 +04:00
Jan Kara
b3de653105 vfs: Reorder operations during sys_sync
Change the order of operations during sync from

for_each_sb {
        writeback_inodes_sb();
        sync_fs(nowait);
        __sync_blockdev(nowait);
}
for_each_sb {
        sync_inodes_sb();
        sync_fs(wait);
        __sync_blockdev(wait);
}

to

for_each_sb
        writeback_inodes_sb();
for_each_sb
        sync_fs(nowait);
for_each_sb
        __sync_blockdev(nowait);
for_each_sb
        sync_inodes_sb();
for_each_sb
        sync_fs(wait);
for_each_sb
        __sync_blockdev(wait);

This is a preparation for the following patches in this series.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-07-22 23:58:41 +04:00
Jan Kara
a117782571 quota: Move quota syncing to ->sync_fs method
Since the moment writes to quota files are using block device page cache and
space for quota structures is reserved at the moment they are first accessed we
have no reason to sync quota before inode writeback. In fact this order is now
only harmful since quota information can easily change during inode writeback
(either because conversion of delayed-allocated extents or simply because of
allocation of new blocks for simple filesystems not using page_mkwrite).

So move syncing of quota information after writeback of inodes into ->sync_fs
method. This way we do not have to use ->quota_sync callback which is primarily
intended for use by quotactl syscall anyway and we get rid of calling
->sync_fs() twice unnecessarily. We skip quota syncing for OCFS2 since it does
proper quota journalling in all cases (unlike ext3, ext4, and reiserfs which
also support legacy non-journalled quotas) and thus there are no dirty quota
structures.

CC: "Theodore Ts'o" <tytso@mit.edu>
CC: Joel Becker <jlbec@evilplan.org>
CC: reiserfs-devel@vger.kernel.org
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Acked-by: Dave Kleikamp <shaggy@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-07-22 23:58:34 +04:00
Jan Kara
ceed17236a quota: Split dquot_quota_sync() to writeback and cache flushing part
Split off part of dquot_quota_sync() which writes dquots into a quota file
to a separate function. In the next patch we will use the function from
filesystems and we do not want to abuse ->quota_sync quotactl callback more
than necessary.

Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-07-22 23:58:19 +04:00
Jan Kara
6eedc70150 vfs: Move noop_backing_dev_info check from sync into writeback
In principle, a filesystem may want to have ->sync_fs() called during sync(1)
although it does not have a bdi (i.e. s_bdi is set to noop_backing_dev_info).
Only writeback code really needs bdi set to something reasonable. So move the
checks where they are more logical.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-07-22 23:58:18 +04:00
Al Viro
c2bd6c11cd switch do_fsync() to fget_light()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-05-29 23:28:29 -04:00
Paul Gortmaker
630d9c4727 fs: reduce the use of module.h wherever possible
For files only using THIS_MODULE and/or EXPORT_SYMBOL, map
them onto including export.h -- or if the file isn't even
using those, then just delete the include.  Fix up any implicit
include dependencies that were being masked by module.h along
the way.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2012-02-28 19:31:58 -05:00
Al Viro
ff01bb4832 fs: move code out of buffer.c
Move invalidate_bdev, block_sync_page into fs/block_dev.c.  Export
kill_bdev as well, so brd doesn't have to open code it.  Reduce
buffer_head.h requirement accordingly.

Removed a rather large comment from invalidate_bdev, as it looked a bit
obsolete to bother moving.  The small comment replacing it says enough.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:54:07 -05:00
Curt Wohlgemuth
0e175a1835 writeback: Add a 'reason' to wb_writeback_work
This creates a new 'reason' field in a wb_writeback_work
structure, which unambiguously identifies who initiates
writeback activity.  A 'wb_reason' enumeration has been
added to writeback.h, to enumerate the possible reasons.

The 'writeback_work_class' and tracepoint event class and
'writeback_queue_io' tracepoints are updated to include the
symbolic 'reason' in all trace events.

And the 'writeback_inodes_sbXXX' family of routines has had
a wb_stats parameter added to them, so callers can specify
why writeback is being started.

Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Curt Wohlgemuth <curtw@google.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-10-31 00:33:36 +08:00
Josef Bacik
02c24a8218 fs: push i_mutex and filemap_write_and_wait down into ->fsync() handlers
Btrfs needs to be able to control how filemap_write_and_wait_range() is called
in fsync to make it less of a painful operation, so push down taking i_mutex and
the calling of filemap_write_and_wait() down into the ->fsync() handlers.  Some
file systems can drop taking the i_mutex altogether it seems, like ext3 and
ocfs2.  For correctness sake I just pushed everything down in all cases to make
sure that we keep the current behavior the same for everybody, and then each
individual fs maintainer can make up their mind about what to do from there.
Thanks,

Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-07-20 20:47:59 -04:00
Linus Torvalds
6c51038900 Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block
* 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block: (65 commits)
  Documentation/iostats.txt: bit-size reference etc.
  cfq-iosched: removing unnecessary think time checking
  cfq-iosched: Don't clear queue stats when preempt.
  blk-throttle: Reset group slice when limits are changed
  blk-cgroup: Only give unaccounted_time under debug
  cfq-iosched: Don't set active queue in preempt
  block: fix non-atomic access to genhd inflight structures
  block: attempt to merge with existing requests on plug flush
  block: NULL dereference on error path in __blkdev_get()
  cfq-iosched: Don't update group weights when on service tree
  fs: assign sb->s_bdi to default_backing_dev_info if the bdi is going away
  block: Require subsystems to explicitly allocate bio_set integrity mempool
  jbd2: finish conversion from WRITE_SYNC_PLUG to WRITE_SYNC and explicit plugging
  jbd: finish conversion from WRITE_SYNC_PLUG to WRITE_SYNC and explicit plugging
  fs: make fsync_buffers_list() plug
  mm: make generic_writepages() use plugging
  blk-cgroup: Add unaccounted time to timeslice_used.
  block: fixup plugging stubs for !CONFIG_BLOCK
  block: remove obsolete comments for blkdev_issue_zeroout.
  blktrace: Use rq->cmd_flags directly in blk_add_trace_rq.
  ...

Fix up conflicts in fs/{aio.c,super.c}
2011-03-24 10:16:26 -07:00
Sage Weil
b7ed78f565 introduce sys_syncfs to sync a single file system
It is frequently useful to sync a single file system, instead of all
mounted file systems via sync(2):

 - On machines with many mounts, it is not at all uncommon for some of
   them to hang (e.g. unresponsive NFS server).  sync(2) will get stuck on
   those and may never get to the one you do care about (e.g., /).
 - Some applications write lots of data to the file system and then
   want to make sure it is flushed to disk.  Calling fsync(2) on each
   file introduces unnecessary ordering constraints that result in a large
   amount of sub-optimal writeback/flush/commit behavior by the file
   system.

There are currently two ways (that I know of) to sync a single super_block:

 - BLKFLSBUF ioctl on the block device: That also invalidates the bdev
   mapping, which isn't usually desirable, and doesn't work for non-block
   file systems.
 - 'mount -o remount,rw' will call sync_filesystem as an artifact of the
   current implemention.  Relying on this little-known side effect for
   something like data safety sounds foolish.

Both of these approaches require root privileges, which some applications
do not have (nor should they need?) given that sync(2) is an unprivileged
operation.

This patch introduces a new system call syncfs(2) that takes an fd and
syncs only the file system it references.  Maybe someday we can

 $ sync /some/path

and not get

 sync: ignoring all arguments

The syscall is motivated by comments by Al and Christoph at the last LSF.
syncfs(2) seems like an appropriate name given statfs(2).

A similar ioctl was also proposed a while back, see
	http://marc.info/?l=linux-fsdevel&m=127970513829285&w=2

Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-03-21 00:40:29 -04:00
Jens Axboe
95f28604a6 fs: assign sb->s_bdi to default_backing_dev_info if the bdi is going away
We don't have proper reference counting for this yet, so we run into
cases where the device is pulled and we OOPS on flushing the fs data.
This happens even though the dirty inodes have already been
migrated to the default_backing_dev_info.

Reported-by: Torsten Hilbrich <torsten.hilbrich@secunet.com>
Tested-by: Torsten Hilbrich <torsten.hilbrich@secunet.com>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-03-17 11:13:12 +01:00
Al Viro
b5fc510c48 get rid of file_fsync()
Copy and simplify in the only two users remaining.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-09 16:47:43 -04:00
Jens Axboe
b4ca761577 Merge branch 'master' into for-linus
Conflicts:
	fs/pipe.c

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-06-01 12:42:12 +02:00
Jens Axboe
0e3c9a2284 Revert "writeback: fix WB_SYNC_NONE writeback from umount"
This reverts commit e913fc825d.

We are investigating a hang associated with the WB_SYNC_NONE changes,
so revert them for now.

Conflicts:

	fs/fs-writeback.c
	mm/page-writeback.c

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-06-01 11:08:43 +02:00
Christoph Hellwig
7ea8085910 drop unused dentry argument to ->fsync
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-05-27 22:05:02 -04:00
Linus Torvalds
e8bebe2f71 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6: (69 commits)
  fix handling of offsets in cris eeprom.c, get rid of fake on-stack files
  get rid of home-grown mutex in cris eeprom.c
  switch ecryptfs_write() to struct inode *, kill on-stack fake files
  switch ecryptfs_get_locked_page() to struct inode *
  simplify access to ecryptfs inodes in ->readpage() and friends
  AFS: Don't put struct file on the stack
  Ban ecryptfs over ecryptfs
  logfs: replace inode uid,gid,mode initialization with helper function
  ufs: replace inode uid,gid,mode initialization with helper function
  udf: replace inode uid,gid,mode init with helper
  ubifs: replace inode uid,gid,mode initialization with helper function
  sysv: replace inode uid,gid,mode initialization with helper function
  reiserfs: replace inode uid,gid,mode initialization with helper function
  ramfs: replace inode uid,gid,mode initialization with helper function
  omfs: replace inode uid,gid,mode initialization with helper function
  bfs: replace inode uid,gid,mode initialization with helper function
  ocfs2: replace inode uid,gid,mode initialization with helper function
  nilfs2: replace inode uid,gid,mode initialization with helper function
  minix: replace inode uid,gid,mode init with helper
  ext4: replace inode uid,gid,mode init with helper
  ...

Trivial conflict in fs/fs-writeback.c (mark bitfields unsigned)
2010-05-21 19:37:45 -07:00
Christoph Hellwig
8018ab0574 sanitize vfs_fsync calling conventions
Now that the last user passing a NULL file pointer is gone we can remove
the redundant dentry argument and associated hacks inside vfs_fsynmc_range.

The next step will be removig the dentry argument from ->fsync, but given
the luck with the last round of method prototype changes I'd rather
defer this until after the main merge window.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-05-21 18:31:21 -04:00
Al Viro
01a05b337a new helper: iterate_supers()
... and switch the simple "loop over superblocks and do something"
loops to it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-05-21 18:31:16 -04:00
Al Viro
8edd64bd60 get rid of restarts in sync_filesystems()
At the same time we can kill s_need_restart and local mutex in there.
__put_super() made public for a while; will be gone later.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-05-21 18:31:15 -04:00
Al Viro
551de6f34d Leave superblocks on s_list until the end
We used to remove from s_list and s_instances at the same
time.  So let's *not* do the former and skip superblocks
that have empty s_instances in the loops over s_list.

The next step, of course, will be to get rid of rescan logics
in those loops.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-05-21 18:31:14 -04:00
Jens Axboe
e913fc825d writeback: fix WB_SYNC_NONE writeback from umount
When umount calls sync_filesystem(), we first do a WB_SYNC_NONE
writeback to kick off writeback of pending dirty inodes, then follow
that up with a WB_SYNC_ALL to wait for it. Since umount already holds
the sb s_umount mutex, WB_SYNC_NONE ends up doing nothing and all
writeback happens as WB_SYNC_ALL. This can greatly slow down umount,
since WB_SYNC_ALL writeback is a data integrity operation and thus
a bigger hammer than simple WB_SYNC_NONE. For barrier aware file systems
it's a lot slower.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2010-05-17 12:55:07 +02:00