linux-stable.git/fs/fs-writeback.c, branch v5.9

fs/fs-writeback.c: adjust dirtytime_interval_handler definition to match prototype

2020-09-19T20:13:39+00:00

Commit 32927393dc1c ("sysctl: pass kernel pointers to ->proc_handler")
changed ctl_table.proc_handler to take a kernel pointer.  Adjust the
definition of dirtytime_interval_handler to match its prototype in
linux/writeback.h which fixes the following sparse error/warning:

fs/fs-writeback.c:2189:50: warning: incorrect type in argument 3 (different address spaces)
fs/fs-writeback.c:2189:50:    expected void *
fs/fs-writeback.c:2189:50:    got void [noderef] __user *buffer
fs/fs-writeback.c:2184:5: error: symbol 'dirtytime_interval_handler' redeclared with different type (incompatible argument 3 (different address spaces)):
fs/fs-writeback.c:2184:5:    int extern [addressable] [signed] [toplevel] dirtytime_interval_handler( ... )
fs/fs-writeback.c: note: in included file:
./include/linux/writeback.h:374:5: note: previously declared as:
./include/linux/writeback.h:374:5:    int extern [addressable] [signed] [toplevel] dirtytime_interval_handler( ... )

Fixes: 32927393dc1c ("sysctl: pass kernel pointers to ->proc_handler")
Signed-off-by: Tobias Klauser 
Signed-off-by: Andrew Morton 
Reviewed-by: Jan Kara 
Cc: Christoph Hellwig 
Cc: Al Viro 
Link: https://lkml.kernel.org/r/20200907093140.13434-1-tklauser@distanz.ch
Signed-off-by: Linus Torvalds

writeback: Drop I_DIRTY_TIME_EXPIRE

2020-06-15T07:18:46+00:00

The only use of I_DIRTY_TIME_EXPIRE is to detect in
__writeback_single_inode() that inode got there because flush worker
decided it's time to writeback the dirty inode time stamps (either
because we are syncing or because of age). However we can detect this
directly in __writeback_single_inode() and there's no need for the
strange propagation with I_DIRTY_TIME_EXPIRE flag.

Reviewed-by: Christoph Hellwig 
Signed-off-by: Jan Kara

writeback: Fix sync livelock due to b_dirty_time processing

2020-06-15T07:18:45+00:00

When we are processing writeback for sync(2), move_expired_inodes()
didn't set any inode expiry value (older_than_this). This can result in
writeback never completing if there's steady stream of inodes added to
b_dirty_time list as writeback rechecks dirty lists after each writeback
round whether there's more work to be done. Fix the problem by using
sync(2) start time is inode expiry value when processing b_dirty_time
list similarly as for ordinarily dirtied inodes. This requires some
refactoring of older_than_this handling which simplifies the code
noticeably as a bonus.

Fixes: 0ae45f63d4ef ("vfs: add support for a lazytime mount option")
CC: stable@vger.kernel.org
Reviewed-by: Christoph Hellwig 
Signed-off-by: Jan Kara

writeback: Avoid skipping inode writeback

2020-06-15T07:18:45+00:00

Inode's i_io_list list head is used to attach inode to several different
lists - wb->{b_dirty, b_dirty_time, b_io, b_more_io}. When flush worker
prepares a list of inodes to writeback e.g. for sync(2), it moves inodes
to b_io list. Thus it is critical for sync(2) data integrity guarantees
that inode is not requeued to any other writeback list when inode is
queued for processing by flush worker. That's the reason why
writeback_single_inode() does not touch i_io_list (unless the inode is
completely clean) and why __mark_inode_dirty() does not touch i_io_list
if I_SYNC flag is set.

However there are two flaws in the current logic:

1) When inode has only I_DIRTY_TIME set but it is already queued in b_io
list due to sync(2), concurrent __mark_inode_dirty(inode, I_DIRTY_SYNC)
can still move inode back to b_dirty list resulting in skipping
writeback of inode time stamps during sync(2).

2) When inode is on b_dirty_time list and writeback_single_inode() races
with __mark_inode_dirty() like:

writeback_single_inode()		__mark_inode_dirty(inode, I_DIRTY_PAGES)
  inode->i_state |= I_SYNC
  __writeback_single_inode()
					  inode->i_state |= I_DIRTY_PAGES;
					  if (inode->i_state & I_SYNC)
					    bail
  if (!(inode->i_state & I_DIRTY_ALL))
  - not true so nothing done

We end up with I_DIRTY_PAGES inode on b_dirty_time list and thus
standard background writeback will not writeback this inode leading to
possible dirty throttling stalls etc. (thanks to Martijn Coenen for this
analysis).

Fix these problems by tracking whether inode is queued in b_io or
b_more_io lists in a new I_SYNC_QUEUED flag. When this flag is set, we
know flush worker has queued inode and we should not touch i_io_list.
On the other hand we also know that once flush worker is done with the
inode it will requeue the inode to appropriate dirty list. When
I_SYNC_QUEUED is not set, __mark_inode_dirty() can (and must) move inode
to appropriate dirty list.

Reported-by: Martijn Coenen 
Reviewed-by: Martijn Coenen 
Tested-by: Martijn Coenen 
Reviewed-by: Christoph Hellwig 
Fixes: 0ae45f63d4ef ("vfs: add support for a lazytime mount option")
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara

writeback: Protect inode->i_io_list with inode->i_lock

2020-06-15T07:18:11+00:00

Currently, operations on inode->i_io_list are protected by
wb->list_lock. In the following patches we'll need to maintain
consistency between inode->i_state and inode->i_io_list so change the
code so that inode->i_lock protects also all inode's i_io_list handling.

Reviewed-by: Martijn Coenen 
Reviewed-by: Christoph Hellwig 
CC: stable@vger.kernel.org # Prerequisite for "writeback: Avoid skipping inode writeback"
Signed-off-by: Jan Kara

Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

2020-06-05T23:19:28+00:00

Pull ext4 updates from Ted Ts'o:
 "A lot of bug fixes and cleanups for ext4, including:

   - Fix performance problems found in dioread_nolock now that it is the
     default, caused by transaction leaks.

   - Clean up fiemap handling in ext4

   - Clean up and refactor multiple block allocator (mballoc) code

   - Fix a problem with mballoc with a smaller file systems running out
     of blocks because they couldn't properly use blocks that had been
     reserved by inode preallocation.

   - Fixed a race in ext4_sync_parent() versus rename()

   - Simplify the error handling in the extent manipulation code

   - Make sure all metadata I/O errors are felected to
     ext4_ext_dirty()'s and ext4_make_inode_dirty()'s callers.

   - Avoid passing an error pointer to brelse in ext4_xattr_set()

   - Fix race which could result to freeing an inode on the dirty last
     in data=journal mode.

   - Fix refcount handling if ext4_iget() fails

   - Fix a crash in generic/019 caused by a corrupted extent node"

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (58 commits)
  ext4: avoid unnecessary transaction starts during writeback
  ext4: don't block for O_DIRECT if IOCB_NOWAIT is set
  ext4: remove the access_ok() check in ext4_ioctl_get_es_cache
  fs: remove the access_ok() check in ioctl_fiemap
  fs: handle FIEMAP_FLAG_SYNC in fiemap_prep
  fs: move fiemap range validation into the file systems instances
  iomap: fix the iomap_fiemap prototype
  fs: move the fiemap definitions out of fs.h
  fs: mark __generic_block_fiemap static
  ext4: remove the call to fiemap_check_flags in ext4_fiemap
  ext4: split _ext4_fiemap
  ext4: fix fiemap size checks for bitmap files
  ext4: fix EXT4_MAX_LOGICAL_BLOCK macro
  add comment for ext4_dir_entry_2 file_type member
  jbd2: avoid leaking transaction credits when unreserving handle
  ext4: drop ext4_journal_free_reserved()
  ext4: mballoc: use lock for checking free blocks while retrying
  ext4: mballoc: refactor ext4_mb_good_group()
  ext4: mballoc: introduce pcpu seqcnt for freeing PA to improve ENOSPC handling
  ext4: mballoc: refactor ext4_mb_discard_preallocations()
  ...

writeback: Export inode_io_list_del()

2020-06-04T03:16:49+00:00

Ext4 needs to remove inode from writeback lists after it is out of
visibility of its journalling machinery (which can still dirty the
inode). Export inode_io_list_del() for it.

Signed-off-by: Jan Kara 
Link: https://lore.kernel.org/r/20200421085445.5731-3-jack@suse.cz
Signed-off-by: Theodore Ts'o

Merge tag 'for-5.8/block-2020-06-01' of git://git.kernel.dk/linux-block

2020-06-02T22:29:19+00:00

Pull block updates from Jens Axboe:
 "Core block changes that have been queued up for this release:

   - Remove dead blk-throttle and blk-wbt code (Guoqing)

   - Include pid in blktrace note traces (Jan)

   - Don't spew I/O errors on wouldblock termination (me)

   - Zone append addition (Johannes, Keith, Damien)

   - IO accounting improvements (Konstantin, Christoph)

   - blk-mq hardware map update improvements (Ming)

   - Scheduler dispatch improvement (Salman)

   - Inline block encryption support (Satya)

   - Request map fixes and improvements (Weiping)

   - blk-iocost tweaks (Tejun)

   - Fix for timeout failing with error injection (Keith)

   - Queue re-run fixes (Douglas)

   - CPU hotplug improvements (Christoph)

   - Queue entry/exit improvements (Christoph)

   - Move DMA drain handling to the few drivers that use it (Christoph)

   - Partition handling cleanups (Christoph)"

* tag 'for-5.8/block-2020-06-01' of git://git.kernel.dk/linux-block: (127 commits)
  block: mark bio_wouldblock_error() bio with BIO_QUIET
  blk-wbt: rename __wbt_update_limits to wbt_update_limits
  blk-wbt: remove wbt_update_limits
  blk-throttle: remove tg_drain_bios
  blk-throttle: remove blk_throtl_drain
  null_blk: force complete for timeout request
  blk-mq: drain I/O when all CPUs in a hctx are offline
  blk-mq: add blk_mq_all_tag_iter
  blk-mq: open code __blk_mq_alloc_request in blk_mq_alloc_request_hctx
  blk-mq: use BLK_MQ_NO_TAG in more places
  blk-mq: rename BLK_MQ_TAG_FAIL to BLK_MQ_NO_TAG
  blk-mq: move more request initialization to blk_mq_rq_ctx_init
  blk-mq: simplify the blk_mq_get_request calling convention
  blk-mq: remove the bio argument to ->prepare_request
  nvme: force complete cancelled requests
  blk-mq: blk-mq: provide forced completion method
  block: fix a warning when blkdev.h is included for !CONFIG_BLOCK builds
  block: blk-crypto-fallback: remove redundant initialization of variable err
  block: reduce part_stat_lock() scope
  block: use __this_cpu_add() instead of access by smp_processor_id()
  ...

mm/writeback: discard NR_UNSTABLE_NFS, use NR_WRITEBACK instead

2020-06-02T17:59:08+00:00

After an NFS page has been written it is considered "unstable" until a
COMMIT request succeeds.  If the COMMIT fails, the page will be
re-written.

These "unstable" pages are currently accounted as "reclaimable", either
in WB_RECLAIMABLE, or in NR_UNSTABLE_NFS which is included in a
'reclaimable' count.  This might have made sense when sending the COMMIT
required a separate action by the VFS/MM (e.g.  releasepage() used to
send a COMMIT).  However now that all writes generated by ->writepages()
will automatically be followed by a COMMIT (since commit 919e3bd9a875
("NFS: Ensure we commit after writeback is complete")) it makes more
sense to treat them as writeback pages.

So this patch removes NR_UNSTABLE_NFS and accounts unstable pages in
NR_WRITEBACK and WB_WRITEBACK.

A particular effect of this change is that when
wb_check_background_flush() calls wb_over_bg_threshold(), the latter
will report 'true' a lot less often as the 'unstable' pages are no
longer considered 'dirty' (as there is nothing that writeback can do
about them anyway).

Currently wb_check_background_flush() will trigger writeback to NFS even
when there are relatively few dirty pages (if there are lots of unstable
pages), this can result in small writes going to the server (10s of
Kilobytes rather than a Megabyte) which hurts throughput.  With this
patch, there are fewer writes which are each larger on average.

Where the NR_UNSTABLE_NFS count was included in statistics
virtual-files, the entry is retained, but the value is hard-coded as
zero.  static trace points and warning printks which mentioned this
counter no longer report it.

[akpm@linux-foundation.org: re-layout comment]
[akpm@linux-foundation.org: fix printk warning]
Signed-off-by: NeilBrown 
Signed-off-by: Andrew Morton 
Reviewed-by: Jan Kara 
Reviewed-by: Christoph Hellwig 
Acked-by: Trond Myklebust 
Acked-by: Michal Hocko 	[mm]
Cc: Christoph Hellwig 
Cc: Chuck Lever 
Link: http://lkml.kernel.org/r/87d06j7gqa.fsf@notabene.neil.brown.name
Signed-off-by: Linus Torvalds

bdi: remove the name field in struct backing_dev_info

2020-05-09T22:15:13+00:00

The name is only printed for a not registered bdi in writeback.  Use the
device name there as is more useful anyway for the unlike case that the
warning triggers.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jan Kara 
Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Bart Van Assche 
Signed-off-by: Jens Axboe