kernel.git/fs/btrfs/extent-tree.c, branch linux-3.2.y

btrfs: clear space cache inode generation always

2018-03-03T15:50:38Z

commit 8e138e0d92c6c9d3d481674fb14e3439b495be37 upstream. We discovered a box that had double allocations, and suspected the space cache may be to blame. While auditing the write out path I noticed that if we've already setup the space cache we will just carry on. This means that any error we hit after cache_save_setup before we go to actually write the cache out we won't reset the inode generation, so whatever was already written will be considered correct, except it'll be stale. Fix this by _always_ resetting the generation on the block group inode, this way we only ever have valid or invalid cache. With this patch I was no longer able to reproduce cache corruption with dm-log-writes and my bpf error injection tool. Signed-off-by: Josef Bacik Signed-off-by: David Sterba Signed-off-by: Ben Hutchings

Btrfs: fix log tree corruption when fs mounted with -o discard

2015-08-06T23:32:01Z

commit dcc82f4783ad91d4ab654f89f37ae9291cdc846a upstream. While committing a transaction we free the log roots before we write the new super block. Freeing the log roots implies marking the disk location of every node/leaf (metadata extent) as pinned before the new super block is written. This is to prevent the disk location of log metadata extents from being reused before the new super block is written, otherwise we would have a corrupted log tree if before the new super block is written a crash/reboot happens and the location of any log tree metadata extent ended up being reused and rewritten. Even though we pinned the log tree's metadata extents, we were issuing a discard against them if the fs was mounted with the -o discard option, resulting in corruption of the log tree if a crash/reboot happened before writing the new super block - the next time the fs was mounted, during the log replay process we would find nodes/leafs of the log btree with a content full of zeroes, causing the process to fail and require the use of the tool btrfs-zero-log to wipeout the log tree (and all data previously fsynced becoming lost forever). Fix this by not doing a discard when pinning an extent. The discard will be done later when it's safe (after the new super block is committed) at extent-tree.c:btrfs_finish_extent_commit(). Fixes: e688b7252f78 (Btrfs: fix extent pinning bugs in the tree log) Signed-off-by: Filipe Manana Signed-off-by: Chris Mason Signed-off-by: Ben Hutchings

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: handle EAGAIN case properly in btrfs_drop_snapshot()

2014-04-01T23:58:45Z

commit 90515e7f5d7d24cbb2a4038a3f1b5cfa2921aa17 upstream. We may return early in btrfs_drop_snapshot(), we shouldn't call btrfs_std_err() for this case, fix it. Signed-off-by: Wang Shilong Signed-off-by: Josef Bacik Signed-off-by: Chris Mason Signed-off-by: Ben Hutchings

Btrfs: re-add root to dead root list if we stop dropping it

2013-08-02T20:15:00Z

commit d29a9f629e009c9b90e5859bce581070fd6247fc upstream. If we stop dropping a root for whatever reason we need to add it back to the dead root list so that we will re-start the dropping next transaction commit. The other case this happens is if we recover a drop because we will add a root without adding it to the fs radix tree, so we can leak it's root and commit root extent buffer, adding this to the dead root list makes this cleanup happen. Thanks, Reported-by: Alex Lyakas Signed-off-by: Josef Bacik [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings

Btrfs: fix lock leak when resuming snapshot deletion

2013-08-02T20:15:00Z

commit fec386ac1428f9c0e672df952cbca5cebd4e4e2f upstream. We aren't setting path->locks[level] when we resume a snapshot deletion which means we won't unlock the buffer when we free the path. This causes deadlocks if we happen to re-allocate the block before we've evicted the extent buffer from cache. Thanks, Reported-by: Alex Lyakas Signed-off-by: Josef Bacik Signed-off-by: Ben Hutchings

Btrfs: limit the global reserve to 512mb

2013-04-10T02:20:05Z

commit fdf30d1c1b386e1b73116cc7e0fb14e962b763b0 upstream. A user reported a problem where he was getting early ENOSPC with hundreds of gigs of free data space and 6 gigs of free metadata space. This is because the global block reserve was taking up the entire free metadata space. This is ridiculous, we have infrastructure in place to throttle if we start using too much of the global reserve, so instead of letting it get this huge just limit it to 512mb so that users can still get work done. This allowed the user to complete his rsync without issues. Thanks Reported-and-tested-by: Stefan Priebe Signed-off-by: Josef Bacik 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: only set cache_generation if we setup the block group

2011-12-15T16:04:24Z

A user reported a problem booting into a new kernel with the old format inodes. He was panicing in cow_file_range while writing out the inode cache. This is because if the block group is not cached we'll just skip writing out the cache, however if it gets dirtied again in the same transaction and it finished caching we'd go ahead and write it out, but since we set cache_generation to the transid we think we've already truncated it and will just carry on, running into cow_file_range and blowing up. We need to make sure we only set cache_generation if we've done the truncate. The user tested this patch and verified that the panic no longer occured. Thanks, Reported-and-Tested-by: Klaus Bitto Signed-off-by: Josef Bacik

Btrfs: fix how we do delalloc reservations and how we free reservations on error

2011-12-15T16:04:22Z

Running xfstests 269 with some tracing my scripts kept spitting out errors about releasing bytes that we didn't actually have reserved. This took me down a huge rabbit hole and it turns out the way we deal with reserved_extents is wrong, we need to only be setting it if the reservation succeeds, otherwise the free() method will come in and unreserve space that isn't actually reserved yet, which can lead to other warnings and such. The math was all working out right in the end, but it caused all sorts of other issues in addition to making my scripts yell and scream and generally make it impossible for me to track down the original issue I was looking for. The other problem is with our error handling in the reservation code. There are two cases that we need to deal with 1) We raced with free. In this case free won't free anything because csum_bytes is modified before we dro the lock in our reservation path, so free rightly doesn't release any space because the reservation code may be depending on that reservation. However if we fail, we need the reservation side to do the free at that point since that space is no longer in use. So as it stands the code was doing this fine and it worked out, except in case #2 2) We don't race with free. Nobody comes in and changes anything, and our reservation fails. In this case we didn't reserve anything anyway and we just need to clean up csum_bytes but not free anything. So we keep track of csum_bytes before we drop the lock and if it hasn't changed we know we can just decrement csum_bytes and carry on. Because of the case where we can race with free()'s since we have to drop our spin_lock to do the reservation, I'm going to serialize all reservations with the i_mutex. We already get this for free in the heavy use paths, truncate and file write all hold the i_mutex, just needed to add it to page_mkwrite and various ioctl/balance things. With this patch my space leak scripts no longer scream bloody murder. Thanks, Signed-off-by: Josef Bacik