kernel.git/fs/btrfs/disk-io.c, branch linux-3.2.y

Btrfs: fix fs corruption on transaction abort if device supports discard

2015-02-20T00:49:30Z

commit 678886bdc6378c1cbd5072da2c5a3035000214e3 upstream. When we abort a transaction we iterate over all the ranges marked as dirty in fs_info->freed_extents[0] and fs_info->freed_extents[1], clear them from those trees, add them back (unpin) to the free space caches and, if the fs was mounted with "-o discard", perform a discard on those regions. Also, after adding the regions to the free space caches, a fitrim ioctl call can see those ranges in a block group's free space cache and perform a discard on the ranges, so the same issue can happen without "-o discard" as well. This causes corruption, affecting one or multiple btree nodes (in the worst case leaving the fs unmountable) because some of those ranges (the ones in the fs_info->pinned_extents tree) correspond to btree nodes/leafs that are referred by the last committed super block - breaking the rule that anything that was committed by a transaction is untouched until the next transaction commits successfully. I ran into this while running in a loop (for several hours) the fstest that I recently submitted: [PATCH] fstests: add btrfs test to stress chunk allocation/removal and fstrim The corruption always happened when a transaction aborted and then fsck complained like this: _check_btrfs_filesystem: filesystem on /dev/sdc is inconsistent *** fsck.btrfs output *** Check tree block failed, want=94945280, have=0 Check tree block failed, want=94945280, have=0 Check tree block failed, want=94945280, have=0 Check tree block failed, want=94945280, have=0 Check tree block failed, want=94945280, have=0 read block failed check_tree_block Couldn't open file system In this case 94945280 corresponded to the root of a tree. Using frace what I observed was the following sequence of steps happened: 1) transaction N started, fs_info->pinned_extents pointed to fs_info->freed_extents[0]; 2) node/eb 94945280 is created; 3) eb is persisted to disk; 4) transaction N commit starts, fs_info->pinned_extents now points to fs_info->freed_extents[1], and transaction N completes; 5) transaction N + 1 starts; 6) eb is COWed, and btrfs_free_tree_block() called for this eb; 7) eb range (94945280 to 94945280 + 16Kb) is added to fs_info->pinned_extents (fs_info->freed_extents[1]); 8) Something goes wrong in transaction N + 1, like hitting ENOSPC for example, and the transaction is aborted, turning the fs into readonly mode. The stack trace I got for example: [112065.253935] [] dump_stack+0x4d/0x66 [112065.254271] [] warn_slowpath_common+0x7f/0x98 [112065.254567] [] ? __btrfs_abort_transaction+0x50/0x10b [btrfs] [112065.261674] [] warn_slowpath_fmt+0x48/0x50 [112065.261922] [] ? btrfs_free_path+0x26/0x29 [btrfs] [112065.262211] [] __btrfs_abort_transaction+0x50/0x10b [btrfs] [112065.262545] [] btrfs_remove_chunk+0x537/0x58b [btrfs] [112065.262771] [] btrfs_delete_unused_bgs+0x1de/0x21b [btrfs] [112065.263105] [] cleaner_kthread+0x100/0x12f [btrfs] (...) [112065.264493] ---[ end trace dd7903a975a31a08 ]--- [112065.264673] BTRFS: error (device sdc) in btrfs_remove_chunk:2625: errno=-28 No space left [112065.264997] BTRFS info (device sdc): forced readonly 9) The clear kthread sees that the BTRFS_FS_STATE_ERROR bit is set in fs_info->fs_state and calls btrfs_cleanup_transaction(), which in turn calls btrfs_destroy_pinned_extent(); 10) Then btrfs_destroy_pinned_extent() iterates over all the ranges marked as dirty in fs_info->freed_extents[], and for each one it calls discard, if the fs was mounted with "-o discard", and adds the range to the free space cache of the respective block group; 11) btrfs_trim_block_group(), invoked from the fitrim ioctl code path, sees the free space entries and performs a discard; 12) After an umount and mount (or fsck), our eb's location on disk was full of zeroes, and it should have been untouched, because it was marked as dirty in the fs_info->pinned_extents tree, and therefore used by the trees that the last committed superblock points to. Fix this by not performing a discard and not adding the ranges to the free space caches - it's useless from this point since the fs is now in readonly mode and we won't write free space caches to disk anymore (otherwise we would leak space) nor any new superblock. By not adding the ranges to the free space caches, it prevents other code paths from allocating that space and write to it as well, therefore being safer and simpler. This isn't a new problem, as it's been present since 2011 (git commit acce952b0263825da32cf10489413dec78053347). Signed-off-by: Filipe Manana Signed-off-by: Chris Mason Signed-off-by: Ben Hutchings

Btrfs: skip submitting barrier for missing device

2014-04-30T15:23:21Z

commit f88ba6a2a44ee98e8d59654463dc157bb6d13c43 upstream. I got an error on v3.13: BTRFS error (device sdf1) in write_all_supers:3378: errno=-5 IO failure (errors while submitting device barriers.) how to reproduce: > mkfs.btrfs -f -d raid1 /dev/sdf1 /dev/sdf2 > wipefs -a /dev/sdf2 > mount -o degraded /dev/sdf1 /mnt > btrfs balance start -f -sconvert=single -mconvert=single -dconvert=single /mnt The reason of the error is that barrier_all_devices() failed to submit barrier to the missing device. However it is clear that we cannot do anything on missing device, and also it is not necessary to care chunks on the missing device. This patch stops sending/waiting barrier if device is missing. Signed-off-by: Hidetoshi Seto Signed-off-by: Josef Bacik Signed-off-by: Ben Hutchings

mm: compaction: introduce sync-light migration for use by compaction

2012-08-02T13:37:32Z

commit a6bc32b899223a877f595ef9ddc1e89ead5072b8 upstream. Stable note: Not tracked in Buzilla. This was part of a series that reduced interactivity stalls experienced when THP was enabled. These stalls were particularly noticable when copying data to a USB stick but the experiences for users varied a lot. This patch adds a lightweight sync migrate operation MIGRATE_SYNC_LIGHT mode that avoids writing back pages to backing storage. Async compaction maps to MIGRATE_ASYNC while sync compaction maps to MIGRATE_SYNC_LIGHT. For other migrate_pages users such as memory hotplug, MIGRATE_SYNC is used. This avoids sync compaction stalling for an excessive length of time, particularly when copying files to a USB stick where there might be a large number of dirty pages backed by a filesystem that does not support ->writepages. [aarcange@redhat.com: This patch is heavily based on Andrea's work] [akpm@linux-foundation.org: fix fs/nfs/write.c build] [akpm@linux-foundation.org: fix fs/btrfs/disk-io.c build] Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel Cc: Andrea Arcangeli Cc: Minchan Kim Cc: Dave Jones Cc: Jan Kara Cc: Andy Isaacson Cc: Nai Xia Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings

mm: compaction: determine if dirty pages can be migrated without blocking within ->migratepage

2012-08-02T13:37:30Z

commit b969c4ab9f182a6e1b2a0848be349f99714947b0 upstream. Stable note: Not tracked in Bugzilla. A fix aimed at preserving page aging information by reducing LRU list churning had the side-effect of reducing THP allocation success rates. This was part of a series to restore the success rates while preserving the reclaim fix. Asynchronous compaction is used when allocating transparent hugepages to avoid blocking for long periods of time. Due to reports of stalling, there was a debate on disabling synchronous compaction but this severely impacted allocation success rates. Part of the reason was that many dirty pages are skipped in asynchronous compaction by the following check; if (PageDirty(page) && !sync && mapping->a_ops->migratepage != migrate_page) rc = -EBUSY; This skips over all mapping aops using buffer_migrate_page() even though it is possible to migrate some of these pages without blocking. This patch updates the ->migratepage callback with a "sync" parameter. It is the responsibility of the callback to fail gracefully if migration would block. Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel Cc: Andrea Arcangeli Cc: Minchan Kim Cc: Dave Jones Cc: Jan Kara Cc: Andy Isaacson Cc: Nai Xia Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings

Merge branches 'for-linus' and 'for-linus-3.2' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs

2011-12-16T20:15:50Z

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: Btrfs: unplug every once and a while Btrfs: deal with NULL srv_rsv in the delalloc inode reservation code Btrfs: only set cache_generation if we setup the block group Btrfs: don't panic if orphan item already exists Btrfs: fix leaked space in truncate Btrfs: fix how we do delalloc reservations and how we free reservations on error Btrfs: deal with enospc from dirtying inodes properly Btrfs: fix num_workers_starting bug and other bugs in async thread BTRFS: Establish i_ops before calling d_instantiate Btrfs: add a cond_resched() into the worker loop Btrfs: fix ctime update of on-disk inode btrfs: keep orphans for subvolume deletion Btrfs: fix inaccurate available space on raid0 profile Btrfs: fix wrong disk space information of the files Btrfs: fix wrong i_size when truncating a file to a larger size Btrfs: fix btrfs_end_bio to deal with write errors to a single mirror * 'for-linus-3.2' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: btrfs: lower the dirty balance poll interval

Btrfs: fix num_workers_starting bug and other bugs in async thread

2011-12-15T16:04:21Z

Al pointed out we have some random problems with the way we account for num_workers_starting in the async thread stuff. First of all we need to make sure to decrement num_workers_starting if we fail to start the worker, so make __btrfs_start_workers do this. Also fix __btrfs_start_workers so that it doesn't call btrfs_stop_workers(), there is no point in stopping everybody if we failed to create a worker. Also check_pending_worker_creates needs to call __btrfs_start_work in it's work function since it already increments num_workers_starting. People only start one worker at a time, so get rid of the num_workers argument everywhere, and make btrfs_queue_worker a void since it will always succeed. Thanks, Signed-off-by: Josef Bacik

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs

2011-11-22T16:53:40Z

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: Btrfs: remove free-space-cache.c WARN during log replay Btrfs: sectorsize align offsets in fiemap Btrfs: clear pages dirty for io and set them extent mapped Btrfs: wait on caching if we're loading the free space cache Btrfs: prefix resize related printks with btrfs: btrfs: fix stat blocks accounting Btrfs: avoid unnecessary bitmap search for cluster setup Btrfs: fix to search one more bitmap for cluster setup btrfs: mirror_num should be int, not u64 btrfs: Fix up 32/64-bit compatibility for new ioctls Btrfs: fix barrier flushes Btrfs: fix tree corruption after multi-thread snapshots and inode_cache flush

btrfs: mirror_num should be int, not u64

2011-11-20T12:42:14Z

My previous patch introduced some u64 for failed_mirror variables, this one makes it consistent again. Signed-off-by: Jan Schmidt Signed-off-by: Chris Mason

Btrfs: fix barrier flushes

2011-11-20T12:21:14Z

When btrfs is writing the super blocks, it send barrier flushes to make sure writeback caching drives get all the metadata on disk in the right order. But, we have two bugs in the way these are sent down. When doing full commits (not via the tree log), we are sending the barrier down before the last super when it should be going down before the first. In multi-device setups, we should be waiting for the barriers to complete on all devices before writing any of the supers. Both of these bugs can cause corruptions on power failures. We fix it with some new code to send down empty barriers to all devices before writing the first super. Alexandre Oliva found the multi-device bug. Arne Jansen did the async barrier loop. Signed-off-by: Chris Mason Reported-by: Alexandre Oliva

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs

2011-11-12T01:47:06Z

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: btrfs: rename the option to nospace_cache Btrfs: handle bio_add_page failure gracefully in scrub Btrfs: fix deadlock caused by the race between relocation Btrfs: only map pages if we know we need them when reading the space cache Btrfs: fix orphan backref nodes Btrfs: Abstract similar code for btrfs_block_rsv_add{, _noflush} Btrfs: fix unreleased path in btrfs_orphan_cleanup() Btrfs: fix no reserved space for writing out inode cache Btrfs: fix nocow when deleting the item Btrfs: tweak the delayed inode reservations again Btrfs: rework error handling in btrfs_mount() Btrfs: close devices on all error paths in open_ctree() Btrfs: avoid null dereference and leaks when bailing from open_ctree() Btrfs: fix subvol_name leak on error in btrfs_mount() Btrfs: fix memory leak in btrfs_parse_early_options() Btrfs: fix our reservations for updating an inode when completing io Btrfs: fix oops on NULL trans handle in btrfs_truncate btrfs: fix double-free 'tree_root' in 'btrfs_mount()'