lwn.git/fs/xfs/xfs_sync.c, branch docs-5.6

xfs: rename xfs_sync.[ch] to xfs_icache.[ch]

2012-10-17T18:40:09+00:00

xfs_sync.c now only contains inode reclaim functions and inode cache iteration functions. It is not related to sync operations anymore. Rename to xfs_icache.c to reflect it's contents and prepare for consolidation with the other inode cache file that exists (xfs_iget.c). Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Reviewed-by: Mark Tinguely Signed-off-by: Ben Myers

xfs: move xfs_quiesce_attr() into xfs_super.c

2012-10-17T18:30:20+00:00

Both callers of xfs_quiesce_attr() are in xfs_super.c, and there's nothing really sync-specific about this functionality so it doesn't really matter where it lives. Move it to benext to it's callers, so all the remount/sync_fs code is in the one place. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Reviewed-by: Mark Tinguely Signed-off-by: Ben Myers

xfs: xfs_sync_fsdata is redundant

2012-10-17T17:28:47+00:00

Why do we need to write the superblock to disk once we've written all the data? We don't actually - the reasons for doing this are lost in the mists of time, and go back to the way Irix used to drive VFS flushing. On linux, this code is only called from two contexts: remount and .sync_fs. In the remount case, the call is followed by a metadata sync, which unpins and writes the superblock. In the sync_fs case, we only need to force the log to disk to ensure that the superblock is correctly on disk, so we don't actually need to write it. Hence the functionality is either redundant or superfluous and thus can be removed. Seeing as xfs_quiesce_data is essentially now just a log force, remove it as well and fold the code back into the two callers. Neither of them need the log covering check, either, as that is redundant for the remount case, and unnecessary for the .sync_fs case. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Reviewed-by: Mark Tinguely Signed-off-by: Ben Myers

xfs: syncd workqueue is no more

2012-10-17T17:19:27+00:00

With the syncd functions moved to the log and/or removed, the syncd workqueue is the only remaining bit left. It is used by the log covering/ail pushing work, as well as by the inode reclaim work. Given how cheap workqueues are these days, give the log and inode reclaim work their own work queues and kill the syncd work queue. Signed-off-by: Dave Chinner Reviewed-by: Mark Tinguely Reviewed-by: Christoph Hellwig Signed-off-by: Ben Myers

xfs: xfs_sync_data is redundant.

2012-10-17T17:01:25+00:00

We don't do any data writeback from XFS any more - the VFS is completely responsible for that, including for freeze. We can replace the remaining caller with a VFS level function that achieves the same thing, but without conflicting with current writeback work. This means we can remove the flush_work and xfs_flush_inodes() - the VFS functionality completely replaces the internal flush queue for doing this writeback work in a separate context to avoid stack overruns. This does have one complication - it cannot be called with page locks held. Hence move the flushing of delalloc space when ENOSPC occurs back up into xfs_file_aio_buffered_write when we don't hold any locks that will stall writeback. Unfortunately, writeback_inodes_sb_if_idle() is not sufficient to trigger delalloc conversion fast enough to prevent spurious ENOSPC whent here are hundreds of writers, thousands of small files and GBs of free RAM. Hence we need to use sync_sb_inodes() to block callers while we wait for writeback like the previous xfs_flush_inodes implementation did. That means we have to hold the s_umount lock here, but because this call can nest inside i_mutex (the parent directory in the create case, held by the VFS), we have to use down_read_trylock() to avoid potential deadlocks. In practice, this trylock will succeed on almost every attempt as unmount/remount type operations are exceedingly rare. Note: we always need to pass a count of zero to generic_file_buffered_write() as the previously written byte count. We only do this by accident before this patch by the virtue of ret always being zero when there are no errors. Make this explicit rather than needing to specifically zero ret in the ENOSPC retry case. Signed-off-by: Dave Chinner Tested-by: Brian Foster Reviewed-by: Christoph Hellwig Signed-off-by: Ben Myers

xfs: sync work is now only periodic log work

2012-10-17T16:53:29+00:00

The only thing the periodic sync work does now is flush the AIL and idle the log. These are really functions of the log code, so move the work to xfs_log.c and rename it appropriately. The only wart that this leaves behind is the xfssyncd_centisecs sysctl, otherwise the xfssyncd is dead. Clean up any comments that related to xfssyncd to reflect it's passing. Signed-off-by: Dave Chinner Reviewed-by: Mark Tinguely Reviewed-by: Christoph Hellwig Signed-off-by: Ben Myers

xfs: don't run the sync work if the filesystem is read-only

2012-10-17T16:48:29+00:00

If the filesystem is mounted or remounted read-only, stop the sync worker that tries to flush or cover the log if the filesystem is dirty. It's read-only, so it isn't dirty. Restart it on a remount,rw as necessary. This avoids the need for RO checks in the work. Similarly, stop the sync work when the filesystem is frozen, and start it again when the filesysetm is thawed. This avoids the need for special freeze checks in the work. Signed-off-by: Dave Chinner Reviewed-by: Mark Tinguely Reviewed-by: Christoph Hellwig Signed-off-by: Ben Myers

xfs: rationalise xfs_mount_wq users

2012-10-17T16:25:06+00:00

Instead of starting and stopping background work on the xfs_mount_wq all at the same time, separate them to where they really are needed to start and stop. The xfs_sync_worker, only needs to be started after all the mount processing has completed successfully, while it needs to be stopped before the log is unmounted. The xfs_reclaim_worker is started on demand, and can be stopped before the unmount process does it's own inode reclaim pass. The xfs_flush_inodes work is run on demand, and so we really only need to ensure that it has stopped running before we start processing an unmount, freeze or remount,ro. Signed-off-by: Dave Chinner Reviewed-by: Mark Tinguely Reviewed-by: Christoph Hellwig Signed-off-by: Ben Myers

xfs: xfs_syncd_stop must die

2012-10-17T16:14:19+00:00

xfs_syncd_start and xfs_syncd_stop tie a bunch of unrelated functionailty together that actually have different start and stop requirements. Kill these functions and open code the start/stop methods for each of the background functions. Subsequent patches will move the start/stop functions around to the correct places to avoid races and shutdown issues. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Reviewed-by: Mark Tinguely Signed-off-by: Ben Myers

workqueue: deprecate flush[_delayed]_work_sync()

2012-08-20T21:51:24+00:00

flush[_delayed]_work_sync() are now spurious. Mark them deprecated and convert all users to flush[_delayed]_work(). If you're cc'd and wondering what's going on: Now all workqueues are non-reentrant and the regular flushes guarantee that the work item is not pending or running on any CPU on return, so there's no reason to use the sync flushes at all and they're going away. This patch doesn't make any functional difference. Signed-off-by: Tejun Heo Cc: Russell King Cc: Paul Mundt Cc: Ian Campbell Cc: Jens Axboe Cc: Mattia Dongili Cc: Kent Yoder Cc: David Airlie Cc: Jiri Kosina Cc: Karsten Keil Cc: Bryan Wu Cc: Benjamin Herrenschmidt Cc: Alasdair Kergon Cc: Mauro Carvalho Chehab Cc: Florian Tobias Schandinat Cc: David Woodhouse Cc: "David S. Miller" Cc: linux-wireless@vger.kernel.org Cc: Anton Vorontsov Cc: Sangbeom Kim Cc: "James E.J. Bottomley" Cc: Greg Kroah-Hartman Cc: Eric Van Hensbergen Cc: Takashi Iwai Cc: Steven Whitehouse Cc: Petr Vandrovec Cc: Mark Fasheh Cc: Christoph Hellwig Cc: Avi Kivity