summaryrefslogtreecommitdiff
path: root/fs/btrfs/btrfs_inode.h
AgeCommit message (Collapse)AuthorFilesLines
2019-04-29Btrfs: improve performance on fsync of files with multiple hardlinksFilipe Manana1-6/+0
Commit 41bd6067692382 ("Btrfs: fix fsync of files with multiple hard links in new directories") introduced a path that makes fsync fallback to a full transaction commit in order to avoid losing hard links and new ancestors of the fsynced inode. That path is triggered only when the inode has more than one hard link and either has a new hard link created in the current transaction or the inode was evicted and reloaded in the current transaction. That path ends up getting triggered very often (hundreds of times) during the course of pgbench benchmarks, resulting in performance drops of about 20%. This change restores the performance by not triggering the full transaction commit in those cases, and instead iterate the fs/subvolume tree in search of all possible new ancestors, for all hard links, to log them. Reported-by: Zhao Yuhu <zyuhu@suse.com> Tested-by: James Wang <jnwang@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2019-04-29btrfs: use common file type conversionPhillip Potter1-2/+0
Deduplicate the btrfs file type conversion implementation - file systems that use the same file types as defined by POSIX do not need to define their own versions and can use the common helper functions decared in fs_types.h and implemented in fs_types.c Common implementation can be found via commit: bbe7449e2599 "fs: common implementation of file type" Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Phillip Potter <phil@philpotter.co.uk> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2018-12-17Btrfs: fix fsync of files with multiple hard links in new directoriesFilipe Manana1-0/+6
The log tree has a long standing problem that when a file is fsync'ed we only check for new ancestors, created in the current transaction, by following only the hard link for which the fsync was issued. We follow the ancestors using the VFS' dget_parent() API. This means that if we create a new link for a file in a directory that is new (or in an any other new ancestor directory) and then fsync the file using an old hard link, we end up not logging the new ancestor, and on log replay that new hard link and ancestor do not exist. In some cases, involving renames, the file will not exist at all. Example: mkfs.btrfs -f /dev/sdb mount /dev/sdb /mnt mkdir /mnt/A touch /mnt/foo ln /mnt/foo /mnt/A/bar xfs_io -c fsync /mnt/foo <power failure> In this example after log replay only the hard link named 'foo' exists and directory A does not exist, which is unexpected. In other major linux filesystems, such as ext4, xfs and f2fs for example, both hard links exist and so does directory A after mounting again the filesystem. Checking if any new ancestors are new and need to be logged was added in 2009 by commit 12fcfd22fe5b ("Btrfs: tree logging unlink/rename fixes"), however only for the ancestors of the hard link (dentry) for which the fsync was issued, instead of checking for all ancestors for all of the inode's hard links. So fix this by tracking the id of the last transaction where a hard link was created for an inode and then on fsync fallback to a full transaction commit when an inode has more than one hard link and at least one new hard link was created in the current transaction. This is the simplest solution since this is not a common use case (adding frequently hard links for which there's an ancestor created in the current transaction and then fsync the file). In case it ever becomes a common use case, a solution that consists of iterating the fs/subvol btree for each hard link and check if any ancestor is new, could be implemented. This solves many unexpected scenarios reported by Jayashree Mohan and Vijay Chidambaram, and for which there is a new test case for fstests under review. Fixes: 12fcfd22fe5b ("Btrfs: tree logging unlink/rename fixes") CC: stable@vger.kernel.org # 4.4+ Reported-by: Vijay Chidambaram <vvijay03@gmail.com> Reported-by: Jayashree Mohan <jayashree2912@gmail.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2018-12-17btrfs: drop extra enum initialization where using defaultsDavid Sterba1-1/+1
The first auto-assigned value to enum is 0, we can use that and not initialize all members where the auto-increment does the same. This is used for values that are not part of on-disk format. Reviewed-by: Omar Sandoval <osandov@fb.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: David Sterba <dsterba@suse.com>
2018-12-17btrfs: use tagged writepage to mitigate livelock of snapshotEthan Lien1-0/+1
Snapshot is expected to be fast. But if there are writers steadily creating dirty pages in our subvolume, the snapshot may take a very long time to complete. To fix the problem, we use tagged writepage for snapshot flusher as we do in the generic write_cache_pages(), so we can omit pages dirtied after the snapshot command. This does not change the semantics regarding which data get to the snapshot, if there are pages being dirtied during the snapshotting operation. There's a sync called before snapshot is taken in old/new case, any IO in flight just after that may be in the snapshot but this depends on other system effects that might still sync the IO. We do a simple snapshot speed test on a Intel D-1531 box: fio --ioengine=libaio --iodepth=32 --bs=4k --rw=write --size=64G --direct=0 --thread=1 --numjobs=1 --time_based --runtime=120 --filename=/mnt/sub/testfile --name=job1 --group_reporting & sleep 5; time btrfs sub snap -r /mnt/sub /mnt/snap; killall fio original: 1m58sec patched: 6.54sec This is the best case for this patch since for a sequential write case, we omit nearly all pages dirtied after the snapshot command. For a multi writers, random write test: fio --ioengine=libaio --iodepth=32 --bs=4k --rw=randwrite --size=64G --direct=0 --thread=1 --numjobs=4 --time_based --runtime=120 --filename=/mnt/sub/testfile --name=job1 --group_reporting & sleep 5; time btrfs sub snap -r /mnt/sub /mnt/snap; killall fio original: 15.83sec patched: 10.35sec The improvement is smaller compared to the sequential write case, since we omit only half of the pages dirtied after snapshot command. Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Ethan Lien <ethanlien@synology.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2018-12-17btrfs: Add function to distinguish between data and btree inodeNikolay Borisov1-0/+5
This will be used in future patches that remove the optional extent_io_ops callbacks. Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2018-10-15btrfs: Remove 'objectid' member from struct btrfs_rootMisono Tomohiro1-4/+4
There are two members in struct btrfs_root which indicate root's objectid: objectid and root_key.objectid. They are both set to the same value in __setup_root(): static void __setup_root(struct btrfs_root *root, struct btrfs_fs_info *fs_info, u64 objectid) { ... root->objectid = objectid; ... root->root_key.objectid = objecitd; ... } and not changed to other value after initialization. grep in btrfs directory shows both are used in many places: $ grep -rI "root->root_key.objectid" | wc -l 133 $ grep -rI "root->objectid" | wc -l 55 (4.17, inc. some noise) It is confusing to have two similar variable names and it seems that there is no rule about which should be used in a certain case. Since ->root_key itself is needed for tree reloc tree, let's remove 'objecitd' member and unify code to use ->root_key.objectid in all places. Signed-off-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2018-08-06btrfs: use timespec64 for i_otimeArnd Bergmann1-1/+1
While the regular inode timestamps all use timespec64 now, the i_otime field is btrfs specific and still needs to be converted to correctly represent times beyond 2038. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28Btrfs: renumber BTRFS_INODE_ runtime flags and switch to enumsOmar Sandoval1-9/+11
We got rid of BTRFS_INODE_HAS_ORPHAN_ITEM and BTRFS_INODE_ORPHAN_META_RESERVED, so we can renumber the flags to make them consecutive again. Signed-off-by: Omar Sandoval <osandov@fb.com> [ switch them enums so we don't have to do that again ] Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28Btrfs: get rid of unused orphan infrastructureOmar Sandoval1-1/+0
Now that we don't keep long-standing reservations for orphan items, root->orphan_block_rsv isn't used. We can git rid of it, along with: - root->orphan_lock, which was used to protect root->orphan_block_rsv - root->orphan_inodes, which was used as a refcount for root->orphan_block_rsv - BTRFS_INODE_ORPHAN_META_RESERVED, which was used to track reservations in root->orphan_block_rsv - btrfs_orphan_commit_root(), which was the last user of any of these and does nothing else Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: David Sterba <dsterba@suse.com>
2018-05-28Btrfs: get rid of BTRFS_INODE_HAS_ORPHAN_ITEMOmar Sandoval1-1/+0
Now that we don't add orphan items for truncate, there can't be races on adding or deleting an orphan item, so this bit is unnecessary. Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: David Sterba <dsterba@suse.com>
2018-04-12btrfs: replace GPL boilerplate by SPDX -- headersDavid Sterba1-16/+3
Remove GPL boilerplate text (long, short, one-line) and keep the rest, ie. personal, company or original source copyright statements. Add the SPDX header. Unify the include protection macros to match the file names. Signed-off-by: David Sterba <dsterba@suse.com>
2018-03-31btrfs: open code trivial helper btrfs_page_exists_in_rangeDavid Sterba1-6/+0
The called function name is self explanatory. Signed-off-by: David Sterba <dsterba@suse.com>
2018-03-31btrfs: Use filemap_range_has_page()Matthew Wilcox1-1/+5
The current implementation of btrfs_page_exists_in_range() gives the wrong answer if the workingset code has stored a shadow entry in the page cache. The filemap_range_has_page() function does not have this problem, and it's shared code, so use it instead. eigned-off-by: Matthew Wilcox <mawilcox@microsoft.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2018-03-26btrfs: Remove btrfs_inode::delayed_iput_countNikolay Borisov1-1/+0
delayed_iput_count wa supposed to be used to implement, well, delayed iput. The idea is that we keep accumulating the number of iputs we do until eventually the inode is deleted. Turns out we never really switched the delayed_iput_count from 0 to 1, hence all conditional code relying on the value of that member being different than 0 was never executed. This, as it turns out, didn't cause any problem due to the simple fact that the generic inode's i_count member was always used to count the number of iputs. So let's just remove the unused member and all unused code. This patch essentially provides no functional changes. While at it, also add proper documentation for btrfs_add_delayed_iput Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> [ reformat comment ] Signed-off-by: David Sterba <dsterba@suse.com>
2017-11-01btrfs: make the delalloc block rsv per inodeJosef Bacik1-17/+9
The way we handle delalloc metadata reservations has gotten progressively more complicated over the years. There is so much cruft and weirdness around keeping the reserved count and outstanding counters consistent and handling the error cases that it's impossible to understand. Fix this by making the delalloc block rsv per-inode. This way we can calculate the actual size of the outstanding metadata reservations every time we make a change, and then reserve the delta based on that amount. This greatly simplifies the code everywhere, and makes the error handling in btrfs_delalloc_reserve_metadata far less terrifying. Signed-off-by: Josef Bacik <jbacik@fb.com> Signed-off-by: David Sterba <dsterba@suse.com>
2017-11-01btrfs: add tracepoints for outstanding extents modsJosef Bacik1-0/+2
This is handy for tracing problems with modifying the outstanding extents counters. Signed-off-by: Josef Bacik <jbacik@fb.com> Signed-off-by: David Sterba <dsterba@suse.com>
2017-11-01Btrfs: rework outstanding_extentsJosef Bacik1-0/+17
Right now we do a lot of weird hoops around outstanding_extents in order to keep the extent count consistent. This is because we logically transfer the outstanding_extent count from the initial reservation through the set_delalloc_bits. This makes it pretty difficult to get a handle on how and when we need to mess with outstanding_extents. Fix this by revamping the rules of how we deal with outstanding_extents. Now instead everybody that is holding on to a delalloc extent is required to increase the outstanding extents count for itself. This means we'll have something like this btrfs_delalloc_reserve_metadata - outstanding_extents = 1 btrfs_set_extent_delalloc - outstanding_extents = 2 btrfs_release_delalloc_extents - outstanding_extents = 1 for an initial file write. Now take the append write where we extend an existing delalloc range but still under the maximum extent size btrfs_delalloc_reserve_metadata - outstanding_extents = 2 btrfs_set_extent_delalloc btrfs_set_bit_hook - outstanding_extents = 3 btrfs_merge_extent_hook - outstanding_extents = 2 btrfs_delalloc_release_extents - outstanding_extnets = 1 In order to make the ordered extent transition we of course must now make ordered extents carry their own outstanding_extent reservation, so for cow_file_range we end up with btrfs_add_ordered_extent - outstanding_extents = 2 clear_extent_bit - outstanding_extents = 1 btrfs_remove_ordered_extent - outstanding_extents = 0 This makes all manipulations of outstanding_extents much more explicit. Every successful call to btrfs_delalloc_reserve_metadata _must_ now be combined with btrfs_release_delalloc_extents, even in the error case, as that is the only function that actually modifies the outstanding_extents counter. The drawback to this is now we are much more likely to have transient cases where outstanding_extents is much larger than it actually should be. This could happen before as we manipulated the delalloc bits, but now it happens basically at every write. This may put more pressure on the ENOSPC flushing code, but I think making this code simpler is worth the cost. I have another change coming to mitigate this side-effect somewhat. I also added trace points for the counter manipulation. These were used by a bpf script I wrote to help track down leak issues. Signed-off-by: Josef Bacik <jbacik@fb.com> Signed-off-by: David Sterba <dsterba@suse.com>
2017-08-16btrfs: separate defrag and property compressionDavid Sterba1-0/+5
Add new value for compression to distinguish between defrag and property. Previously, a single variable was used and this caused clashes when the per-file 'compression' was set and a defrag -c was called. The property-compression is loaded when the file is open, defrag will overwrite the same variable and reset to 0 (ie. NONE) at when the file defragmentaion is finished. That's considered a usability bug. Now we won't touch the property value, use the defrag-compression. The precedence of defrag is higher than for property (and whole-filesystem). Signed-off-by: David Sterba <dsterba@suse.com>
2017-08-16btrfs: rename variable holding per-inode compression typeDavid Sterba1-2/+2
This is preparatory for separating inode compression requested by defrag and set via properties. This will fix a usability bug when defrag will reset compression type to NONE. If the file has compression set via property, it will not apply anymore (until next mount or reset through command line). We're going to fix that by adding another variable just for the defrag call and won't touch the property. The defrag will have higher priority when deciding whether to compress the data. Signed-off-by: David Sterba <dsterba@suse.com>
2017-08-16btrfs: constify tracepoint argumentsJeff Mahoney1-2/+2
Tracepoint arguments are all read-only. If we mark the arguments as const, we're able to keep or convert those arguments to const where appropriate. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2017-06-09block: switch bios to blk_status_tChristoph Hellwig1-1/+2
Replace bi_error with a new bi_status to allow for a clear conversion. Note that device mapper overloaded bi_error with a private value, which we'll have to keep arround at least for now and thus propagate to a proper blk_status_t value. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-26Btrfs: fix reported number of inode blocksFilipe Manana1-0/+7
Currently when there are buffered writes that were not yet flushed and they fall within allocated ranges of the file (that is, not in holes or beyond eof assuming there are no prealloc extents beyond eof), btrfs simply reports an incorrect number of used blocks through the stat(2) system call (or any of its variants), regardless of mount options or inode flags (compress, compress-force, nodatacow). This is because the number of blocks used that is reported is based on the current number of bytes in the vfs inode plus the number of dealloc bytes in the btrfs inode. The later covers bytes that both fall within allocated regions of the file and holes. Example scenarios where the number of reported blocks is wrong while the buffered writes are not flushed: $ mkfs.btrfs -f /dev/sdc $ mount /dev/sdc /mnt/sdc $ xfs_io -f -c "pwrite -S 0xaa 0 64K" /mnt/sdc/foo1 wrote 65536/65536 bytes at offset 0 64 KiB, 16 ops; 0.0000 sec (259.336 MiB/sec and 66390.0415 ops/sec) $ sync $ xfs_io -c "pwrite -S 0xbb 0 64K" /mnt/sdc/foo1 wrote 65536/65536 bytes at offset 0 64 KiB, 16 ops; 0.0000 sec (192.308 MiB/sec and 49230.7692 ops/sec) # The following should have reported 64K... $ du -h /mnt/sdc/foo1 128K /mnt/sdc/foo1 $ sync # After flushing the buffered write, it now reports the correct value. $ du -h /mnt/sdc/foo1 64K /mnt/sdc/foo1 $ xfs_io -f -c "falloc -k 0 128K" -c "pwrite -S 0xaa 0 64K" /mnt/sdc/foo2 wrote 65536/65536 bytes at offset 0 64 KiB, 16 ops; 0.0000 sec (520.833 MiB/sec and 133333.3333 ops/sec) $ sync $ xfs_io -c "pwrite -S 0xbb 64K 64K" /mnt/sdc/foo2 wrote 65536/65536 bytes at offset 65536 64 KiB, 16 ops; 0.0000 sec (260.417 MiB/sec and 66666.6667 ops/sec) # The following should have reported 128K... $ du -h /mnt/sdc/foo2 192K /mnt/sdc/foo2 $ sync # After flushing the buffered write, it now reports the correct value. $ du -h /mnt/sdc/foo2 128K /mnt/sdc/foo2 So the number of used file blocks is simply incorrect, unlike in other filesystems such as ext4 and xfs for example, but only while the buffered writes are not flushed. Fix this by tracking the number of delalloc bytes that fall within holes and beyond eof of a file, and use instead this new counter when reporting the number of used blocks for an inode. Another different problem that exists is that the delalloc bytes counter is reset when writeback starts (by clearing the EXTENT_DEALLOC flag from the respective range in the inode's iotree) and the vfs inode's bytes counter is only incremented when writeback finishes (through insert_reserved_file_extent()). Therefore while writeback is ongoing we simply report a wrong number of blocks used by an inode if the write operation covers a range previously unallocated. While this change does not fix this problem, it does minimizes it a lot by shortening that time window, as the new dealloc bytes counter (new_delalloc_bytes) is only decremented when writeback finishes right before updating the vfs inode's bytes counter. Fully fixing this second problem is not trivial and will be addressed later by a different patch. Signed-off-by: Filipe Manana <fdmanana@suse.com>
2017-02-28btrfs: make btrfs_inode_resume_unlocked_dio take btrfs_inodeNikolay Borisov1-3/+2
Signed-off-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2017-02-28btrfs: make btrfs_inode_block_unlocked_dio take btrfs_inodeNikolay Borisov1-2/+2
Signed-off-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2017-02-28btrfs: make btrfs_print_data_csum_error take btrfs_inodeNikolay Borisov1-4/+4
Signed-off-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2017-02-28btrfs: make btrfs_is_free_space_inode take btrfs_inodeNikolay Borisov1-4/+4
Signed-off-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2017-02-28btrfs: Make btrfs_i_size_write take btrfs_inodeNikolay Borisov1-3/+3
Signed-off-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2017-02-17btrfs: Better csum error message for data csum mismatchQu Wenruo1-0/+18
The original csum error message only outputs inode number, offset, check sum and expected check sum. However no root objectid is outputted, which sometimes makes debugging quite painful under multi-subvolume case (including relocation). Also the checksum output is decimal, which seldom makes sense for users/developers and is hard to read in most time. This patch will add root objectid, which will be %lld for rootid larger than LAST_FREE_OBJECTID, and hex csum output for better readability. Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2017-02-14btrfs: Make btrfs_inode_in_log take btrfs_inodeNikolay Borisov1-9/+7
Signed-off-by: Nikolay Borisov <n.borisov.lkml@gmail.com> Signed-off-by: David Sterba <dsterba@suse.com>
2017-02-14btrfs: Make btrfs_ino take a struct btrfs_inodeNikolay Borisov1-5/+5
Currently btrfs_ino takes a struct inode and this causes a lot of internal btrfs functions which consume this ino to take a VFS inode, rather than btrfs' own struct btrfs_inode. In order to fix this "leak" of VFS structs into the internals of btrfs first it's necessary to eliminate all uses of struct inode for the purpose of inode. This patch does that by using BTRFS_I to convert an inode to btrfs_inode. With this problem eliminated subsequent patches will start eliminating the passing of struct inode altogether, eventually resulting in a lot cleaner code. Signed-off-by: Nikolay Borisov <n.borisov.lkml@gmail.com> [ fix btrfs_get_extent tracepoint prototype ] Signed-off-by: David Sterba <dsterba@suse.com>
2016-09-26Btrfs: add a flags field to btrfs_fs_infoJosef Bacik1-11/+0
We have a lot of random ints in btrfs_fs_info that can be put into flags. This is mostly equivalent with the exception of how we deal with quota going on or off, now instead we set a flag when we are turning it on or off and deal with that appropriately, rather than just having a pending state that the current quota_enabled gets set to. Thanks, Signed-off-by: Josef Bacik <jbacik@fb.com> Signed-off-by: David Sterba <dsterba@suse.com>
2016-05-25Merge branch 'cleanups-4.7' into for-chris-4.7-20160525David Sterba1-1/+1
2016-05-25btrfs: fix string and comment grammatical issues and typosNicholas D Steeves1-1/+1
Signed-off-by: Nicholas D Steeves <nsteeves@gmail.com> Signed-off-by: David Sterba <dsterba@suse.com>
2016-05-13Btrfs: add semaphore to synchronize direct IO writes with fsyncFilipe Manana1-0/+10
Due to the optimization of lockless direct IO writes (the inode's i_mutex is not held) introduced in commit 38851cc19adb ("Btrfs: implement unlocked dio write"), we started having races between such writes with concurrent fsync operations that use the fast fsync path. These races were addressed in the patches titled "Btrfs: fix race between fsync and lockless direct IO writes" and "Btrfs: fix race between fsync and direct IO writes for prealloc extents". The races happened because the direct IO path, like every other write path, does create extent maps followed by the corresponding ordered extents while the fast fsync path collected first ordered extents and then it collected extent maps. This made it possible to log file extent items (based on the collected extent maps) without waiting for the corresponding ordered extents to complete (get their IO done). The two fixes mentioned before added a solution that consists of making the direct IO path create first the ordered extents and then the extent maps, while the fsync path attempts to collect any new ordered extents once it collects the extent maps. This was simple and did not require adding any synchonization primitive to any data structure (struct btrfs_inode for example) but it makes things more fragile for future development endeavours and adds an exceptional approach compared to the other write paths. This change adds a read-write semaphore to the btrfs inode structure and makes the direct IO path create the extent maps and the ordered extents while holding read access on that semaphore, while the fast fsync path collects extent maps and ordered extents while holding write access on that semaphore. The logic for direct IO write path is encapsulated in a new helper function that is used both for cow and nocow direct IO writes. Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: Josef Bacik <jbacik@fb.com>
2016-01-07btrfs: put delayed item hook into inodeDavid Sterba1-0/+4
Inodes for delayed iput allocate a trivial helper structure, let's place the list hook directly into the inode and save a kmalloc (killing a __GFP_NOFAIL as a bonus) at the cost of increasing size of btrfs_inode. The inode can be put into the delayed_iputs list more than once and we have to keep the count. This means we can't use the list_splice to process a bunch of inodes because we'd lost track of the count if the inode is put into the delayed iputs again while it's processed. Signed-off-by: David Sterba <dsterba@suse.com>
2015-09-21Btrfs: Direct I/O: Fix space accountingchandan1-2/+0
The following call trace is seen when generic/095 test is executed, WARNING: CPU: 3 PID: 2769 at /home/chandan/code/repos/linux/fs/btrfs/inode.c:8967 btrfs_destroy_inode+0x284/0x2a0() Modules linked in: CPU: 3 PID: 2769 Comm: umount Not tainted 4.2.0-rc5+ #31 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20150306_163512-brownie 04/01/2014 ffffffff81c08150 ffff8802ec9cbce8 ffffffff81984058 ffff8802ffd8feb0 0000000000000000 ffff8802ec9cbd28 ffffffff81050385 ffff8802ec9cbd38 ffff8802d12f8588 ffff8802d12f8588 ffff8802f15ab000 ffff8800bb96c0b0 Call Trace: [<ffffffff81984058>] dump_stack+0x45/0x57 [<ffffffff81050385>] warn_slowpath_common+0x85/0xc0 [<ffffffff81050465>] warn_slowpath_null+0x15/0x20 [<ffffffff81340294>] btrfs_destroy_inode+0x284/0x2a0 [<ffffffff8117ce07>] destroy_inode+0x37/0x60 [<ffffffff8117cf39>] evict+0x109/0x170 [<ffffffff8117cfd5>] dispose_list+0x35/0x50 [<ffffffff8117dd3a>] evict_inodes+0xaa/0x100 [<ffffffff81165667>] generic_shutdown_super+0x47/0xf0 [<ffffffff81165951>] kill_anon_super+0x11/0x20 [<ffffffff81302093>] btrfs_kill_super+0x13/0x110 [<ffffffff81165c99>] deactivate_locked_super+0x39/0x70 [<ffffffff811660cf>] deactivate_super+0x5f/0x70 [<ffffffff81180e1e>] cleanup_mnt+0x3e/0x90 [<ffffffff81180ebd>] __cleanup_mnt+0xd/0x10 [<ffffffff81069c06>] task_work_run+0x96/0xb0 [<ffffffff81003a3d>] do_notify_resume+0x3d/0x50 [<ffffffff8198cbc2>] int_signal+0x12/0x17 This means that the inode had non-zero "outstanding extents" during eviction. This occurs because, during direct I/O a task which successfully used up its reserved data space would set BTRFS_INODE_DIO_READY bit and does not clear the bit after finishing the DIO write. A future DIO write could actually fail and the unused reserve space won't be freed because of the previously set BTRFS_INODE_DIO_READY bit. Clearing the BTRFS_INODE_DIO_READY bit in btrfs_direct_IO() caused the following issue, |-----------------------------------+-------------------------------------| | Task A | Task B | |-----------------------------------+-------------------------------------| | Start direct i/o write on inode X.| | | reserve space | | | Allocate ordered extent | | | release reserved space | | | Set BTRFS_INODE_DIO_READY bit. | | | | splice() | | | Transfer data from pipe buffer to | | | destination file. | | | - kmap(pipe buffer page) | | | - Start direct i/o write on | | | inode X. | | | - reserve space | | | - dio_refill_pages() | | | - sdio->blocks_available == 0 | | | - Since a kernel address is | | | being passed instead of a | | | user space address, | | | iov_iter_get_pages() returns | | | -EFAULT. | | | - Since BTRFS_INODE_DIO_READY is | | | set, we don't release reserved | | | space. | | | - Clear BTRFS_INODE_DIO_READY bit.| | -EIOCBQUEUED is returned. | | |-----------------------------------+-------------------------------------| Hence this commit introduces "struct btrfs_dio_data" to track the usage of reserved data space. The remaining unused "reserve space" can now be freed reliably. Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com> Reviewed-by: Liu Bo <bo.li.liu@oracle.com> Signed-off-by: Chris Mason <clm@fb.com>
2015-07-02Btrfs: fix warning of bytes_may_useLiu Bo1-0/+2
While running generic/019, dmesg got several warnings from btrfs_free_reserved_data_space(). Test generic/019 produces some disk failures so sumbit dio will get errors, in which case, btrfs_direct_IO() goes to the error handling and free bytes_may_use, but the problem is that bytes_may_use has been free'd during get_block(). This adds a runtime flag to show if we've gone through get_block(), if so, don't do the cleanup work. Signed-off-by: Liu Bo <bo.li.liu@oracle.com> Reviewed-by: Filipe Manana <fdmanana@suse.com> Tested-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Chris Mason <clm@fb.com>
2015-03-27Btrfs: fix metadata inconsistencies after directory fsyncFilipe Manana1-3/+11
We can get into inconsistency between inodes and directory entries after fsyncing a directory. The issue is that while a directory gets the new dentries persisted in the fsync log and replayed at mount time, the link count of the inode that directory entries point to doesn't get updated, staying with an incorrect link count (smaller then the correct value). This later leads to stale file handle errors when accessing (including attempt to delete) some of the links if all the other ones are removed, which also implies impossibility to delete the parent directories, since the dentries can not be removed. Another issue is that (unlike ext3/4, xfs, f2fs, reiserfs, nilfs2), when fsyncing a directory, new files aren't logged (their metadata and dentries) nor any child directories. So this patch fixes this issue too, since it has the same resolution as the incorrect inode link count issue mentioned before. This is very easy to reproduce, and the following excerpt from my test case for xfstests shows how: _scratch_mkfs >> $seqres.full 2>&1 _init_flakey _mount_flakey # Create our main test file and directory. $XFS_IO_PROG -f -c "pwrite -S 0xaa 0 8K" $SCRATCH_MNT/foo | _filter_xfs_io mkdir $SCRATCH_MNT/mydir # Make sure all metadata and data are durably persisted. sync # Add a hard link to 'foo' inside our test directory and fsync only the # directory. The btrfs fsync implementation had a bug that caused the new # directory entry to be visible after the fsync log replay but, the inode # of our file remained with a link count of 1. ln $SCRATCH_MNT/foo $SCRATCH_MNT/mydir/foo_2 # Add a few more links and new files. # This is just to verify nothing breaks or gives incorrect results after the # fsync log is replayed. ln $SCRATCH_MNT/foo $SCRATCH_MNT/mydir/foo_3 $XFS_IO_PROG -f -c "pwrite -S 0xff 0 64K" $SCRATCH_MNT/hello | _filter_xfs_io ln $SCRATCH_MNT/hello $SCRATCH_MNT/mydir/hello_2 # Add some subdirectories and new files and links to them. This is to verify # that after fsyncing our top level directory 'mydir', all the subdirectories # and their files/links are registered in the fsync log and exist after the # fsync log is replayed. mkdir -p $SCRATCH_MNT/mydir/x/y/z ln $SCRATCH_MNT/foo $SCRATCH_MNT/mydir/x/y/foo_y_link ln $SCRATCH_MNT/foo $SCRATCH_MNT/mydir/x/y/z/foo_z_link touch $SCRATCH_MNT/mydir/x/y/z/qwerty # Now fsync only our top directory. $XFS_IO_PROG -c "fsync" $SCRATCH_MNT/mydir # And fsync now our new file named 'hello', just to verify later that it has # the expected content and that the previous fsync on the directory 'mydir' had # no bad influence on this fsync. $XFS_IO_PROG -c "fsync" $SCRATCH_MNT/hello # Simulate a crash/power loss. _load_flakey_table $FLAKEY_DROP_WRITES _unmount_flakey _load_flakey_table $FLAKEY_ALLOW_WRITES _mount_flakey # Verify the content of our file 'foo' remains the same as before, 8192 bytes, # all with the value 0xaa. echo "File 'foo' content after log replay:" od -t x1 $SCRATCH_MNT/foo # Remove the first name of our inode. Because of the directory fsync bug, the # inode's link count was 1 instead of 5, so removing the 'foo' name ended up # deleting the inode and the other names became stale directory entries (still # visible to applications). Attempting to remove or access the remaining # dentries pointing to that inode resulted in stale file handle errors and # made it impossible to remove the parent directories since it was impossible # for them to become empty. echo "file 'foo' link count after log replay: $(stat -c %h $SCRATCH_MNT/foo)" rm -f $SCRATCH_MNT/foo # Now verify that all files, links and directories created before fsyncing our # directory exist after the fsync log was replayed. [ -f $SCRATCH_MNT/mydir/foo_2 ] || echo "Link mydir/foo_2 is missing" [ -f $SCRATCH_MNT/mydir/foo_3 ] || echo "Link mydir/foo_3 is missing" [ -f $SCRATCH_MNT/hello ] || echo "File hello is missing" [ -f $SCRATCH_MNT/mydir/hello_2 ] || echo "Link mydir/hello_2 is missing" [ -f $SCRATCH_MNT/mydir/x/y/foo_y_link ] || \ echo "Link mydir/x/y/foo_y_link is missing" [ -f $SCRATCH_MNT/mydir/x/y/z/foo_z_link ] || \ echo "Link mydir/x/y/z/foo_z_link is missing" [ -f $SCRATCH_MNT/mydir/x/y/z/qwerty ] || \ echo "File mydir/x/y/z/qwerty is missing" # We expect our file here to have a size of 64Kb and all the bytes having the # value 0xff. echo "file 'hello' content after log replay:" od -t x1 $SCRATCH_MNT/hello # Now remove all files/links, under our test directory 'mydir', and verify we # can remove all the directories. rm -f $SCRATCH_MNT/mydir/x/y/z/* rmdir $SCRATCH_MNT/mydir/x/y/z rm -f $SCRATCH_MNT/mydir/x/y/* rmdir $SCRATCH_MNT/mydir/x/y rmdir $SCRATCH_MNT/mydir/x rm -f $SCRATCH_MNT/mydir/* rmdir $SCRATCH_MNT/mydir # An fsck, run by the fstests framework everytime a test finishes, also detected # the inconsistency and printed the following error message: # # root 5 inode 257 errors 2001, no inode item, link count wrong # unresolved ref dir 258 index 2 namelen 5 name foo_2 filetype 1 errors 4, no inode ref # unresolved ref dir 258 index 3 namelen 5 name foo_3 filetype 1 errors 4, no inode ref status=0 exit The expected golden output for the test is: wrote 8192/8192 bytes at offset 0 XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) wrote 65536/65536 bytes at offset 0 XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) File 'foo' content after log replay: 0000000 aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa * 0020000 file 'foo' link count after log replay: 5 file 'hello' content after log replay: 0000000 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff * 0200000 Which is the output after this patch and when running the test against ext3/4, xfs, f2fs, reiserfs or nilfs2. Without this patch, the test's output is: wrote 8192/8192 bytes at offset 0 XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) wrote 65536/65536 bytes at offset 0 XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) File 'foo' content after log replay: 0000000 aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa * 0020000 file 'foo' link count after log replay: 1 Link mydir/foo_2 is missing Link mydir/foo_3 is missing Link mydir/x/y/foo_y_link is missing Link mydir/x/y/z/foo_z_link is missing File mydir/x/y/z/qwerty is missing file 'hello' content after log replay: 0000000 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff * 0200000 rmdir: failed to remove '/home/fdmanana/btrfs-tests/scratch_1/mydir/x/y/z': No such file or directory rmdir: failed to remove '/home/fdmanana/btrfs-tests/scratch_1/mydir/x/y': No such file or directory rmdir: failed to remove '/home/fdmanana/btrfs-tests/scratch_1/mydir/x': No such file or directory rm: cannot remove '/home/fdmanana/btrfs-tests/scratch_1/mydir/foo_2': Stale file handle rm: cannot remove '/home/fdmanana/btrfs-tests/scratch_1/mydir/foo_3': Stale file handle rmdir: failed to remove '/home/fdmanana/btrfs-tests/scratch_1/mydir': Directory not empty Fsck, without this fix, also complains about the wrong link count: root 5 inode 257 errors 2001, no inode item, link count wrong unresolved ref dir 258 index 2 namelen 5 name foo_2 filetype 1 errors 4, no inode ref unresolved ref dir 258 index 3 namelen 5 name foo_3 filetype 1 errors 4, no inode ref So fix this by logging the inodes that the dentries point to when fsyncing a directory. A test case for xfstests follows. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Chris Mason <clm@fb.com>
2015-02-03Btrfs: Add code to support file creation timechandan r1-0/+3
This patch adds a new member to the 'struct btrfs_inode' structure to hold the file creation time. Signed-off-by: chandan <chandanrmail@gmail.com> [refreshed, removed btrfs_inode_otime] Signed-off-by: David Sterba <dsterba@suse.cz> Signed-off-by: Chris Mason <clm@fb.com>
2014-10-11Merge branch 'for-linus' of ↵Linus Torvalds1-1/+26
git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs Pull btrfs updates from Chris Mason: "The largest set of changes here come from Miao Xie. He's cleaning up and improving read recovery/repair for raid, and has a number of related fixes. I've merged another set of fsync fixes from Filipe, and he's also improved the way we handle metadata write errors to make sure we force the FS readonly if things go wrong. Otherwise we have a collection of fixes and cleanups. Dave Sterba gets a cookie for removing the most lines (thanks Dave)" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: (139 commits) btrfs: Fix compile error when CONFIG_SECURITY is not set. Btrfs: fix compiles when CONFIG_BTRFS_FS_RUN_SANITY_TESTS is off btrfs: Make btrfs handle security mount options internally to avoid losing security label. Btrfs: send, don't delay dir move if there's a new parent inode btrfs: add more superblock checks Btrfs: fix race in WAIT_SYNC ioctl Btrfs: be aware of btree inode write errors to avoid fs corruption Btrfs: remove redundant btrfs_verify_qgroup_counts declaration. btrfs: fix shadow warning on cmp Btrfs: fix compilation errors under DEBUG Btrfs: fix crash of btrfs_release_extent_buffer_page Btrfs: add missing end_page_writeback on submit_extent_page failure btrfs: Fix the wrong condition judgment about subset extent map Btrfs: fix build_backref_tree issue with multiple shared blocks Btrfs: cleanup error handling in build_backref_tree btrfs: move checks for DUMMY_ROOT into a helper btrfs: new define for the inline extent data start btrfs: kill extent_buffer_page helper btrfs: drop constant param from btrfs_release_extent_buffer_page btrfs: hide typecast to definition of BTRFS_SEND_TRANS_STUB ...
2014-10-04Btrfs: be aware of btree inode write errors to avoid fs corruptionFilipe Manana1-0/+11
While we have a transaction ongoing, the VM might decide at any time to call btree_inode->i_mapping->a_ops->writepages(), which will start writeback of dirty pages belonging to btree nodes/leafs. This call might return an error or the writeback might finish with an error before we attempt to commit the running transaction. If this happens, we might have no way of knowing that such error happened when we are committing the transaction - because the pages might no longer be marked dirty nor tagged for writeback (if a subsequent modification to the extent buffer didn't happen before the transaction commit) which makes filemap_fdata[write|wait]_range unable to find such pages (even if they're marked with SetPageError). So if this happens we must abort the transaction, otherwise we commit a super block with btree roots that point to btree nodes/leafs whose content on disk is invalid - either garbage or the content of some node/leaf from a past generation that got cowed or deleted and is no longer valid (for this later case we end up getting error messages like "parent transid verify failed on 10826481664 wanted 25748 found 29562" when reading btree nodes/leafs from disk). Note that setting and checking AS_EIO/AS_ENOSPC in the btree inode's i_mapping would not be enough because we need to distinguish between log tree extents (not fatal) vs non-log tree extents (fatal) and because the next call to filemap_fdatawait_range() will catch and clear such errors in the mapping - and that call might be from a log sync and not from a transaction commit, which means we would not know about the error at transaction commit time. Also, checking for the eb flag EXTENT_BUFFER_IOERR at transaction commit time isn't done and would not be completely reliable, as the eb might be removed from memory and read back when trying to get it, which clears that flag right before reading the eb's pages from disk, making us not know about the previous write error. Using the new 3 flags for the btree inode also makes us achieve the goal of AS_EIO/AS_ENOSPC when writepages() returns success, started writeback for all dirty pages and before filemap_fdatawait_range() is called, the writeback for all dirty pages had already finished with errors - because we were not using AS_EIO/AS_ENOSPC, filemap_fdatawait_range() would return success, as it could not know that writeback errors happened (the pages were no longer tagged for writeback). Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Chris Mason <clm@fb.com>
2014-09-18Btrfs: implement repair function when direct read failsMiao Xie1-1/+1
This patch implement data repair function when direct read fails. The detail of the implementation is: - When we find the data is not right, we try to read the data from the other mirror. - When the io on the mirror ends, we will insert the endio work into the dedicated btrfs workqueue, not common read endio workqueue, because the original endio work is still blocked in the btrfs endio workqueue, if we insert the endio work of the io on the mirror into that workqueue, deadlock would happen. - After we get right data, we write it back to the corrupted mirror. - And if the data on the new mirror is still corrupted, we will try next mirror until we read right data or all the mirrors are traversed. - After the above work, we set the uptodate flag according to the result. Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Chris Mason <clm@fb.com>
2014-09-18Btrfs: do file data check by sub-bio's selfMiao Xie1-0/+9
Direct IO splits the original bio to several sub-bios because of the limit of raid stripe, and the filesystem will wait for all sub-bios and then run final end io process. But it was very hard to implement the data repair when dio read failure happens, because at the final end io function, we didn't know which mirror the data was read from. So in order to implement the data repair, we have to move the file data check in the final end io function to the sub-bio end io function, in which we can get the mirror number of the device we access. This patch did this work as the first step of the direct io data repair implementation. Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Chris Mason <clm@fb.com>
2014-09-18Btrfs: load checksum data once when submitting a direct read ioMiao Xie1-1/+0
The current code would load checksum data for several times when we split a whole direct read io because of the limit of the raid stripe, it would make us search the csum tree for several times. In fact, it just wasted time, and made the contention of the csum tree root be more serious. This patch improves this problem by loading the data at once. Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Chris Mason <clm@fb.com>
2014-09-18Btrfs: make defragment work with nodatacow optionWang Shilong1-0/+6
Btrfs defragment will utilize COW feature, which means this did not work for nodatacow option, this problem was detected by xfstests generic/018 with nodatacow mount option. Fix this problem by forcing cow for a extent with state @EXTETN_DEFRAG setting. Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com> Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Chris Mason <clm@fb.com>
2014-09-17Btrfs: set inode's logged_trans/last_log_commit after ranged fsyncFilipe Manana1-2/+11
When a ranged fsync finishes if there are still extent maps in the modified list, still set the inode's logged_trans and last_log_commit. This is important in case an inode is fsync'ed and unlinked in the same transaction, to ensure its inode ref gets deleted from the log and the respective dentries in its parent are deleted too from the log (if the parent directory was fsync'ed in the same transaction). Instead make btrfs_inode_in_log() return false if the list of modified extent maps isn't empty. This is an incremental on top of the v4 version of the patch: "Btrfs: fix fsync data loss after a ranged fsync" which was added to its v5, but didn't make it on time. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Chris Mason <clm@fb.com>
2014-08-15btrfs: disable strict file flushes for renames and truncatesChris Mason1-6/+0
Truncates and renames are often used to replace old versions of a file with new versions. Applications often expect this to be an atomic replacement, even if they haven't done anything to make sure the new version is fully on disk. Btrfs has strict flushing in place to make sure that renaming over an old file with a new file will fully flush out the new file before allowing the transaction commit with the rename to complete. This ordering means the commit code needs to be able to lock file pages, and there are a few paths in the filesystem where we will try to end a transaction with the page lock held. It's rare, but these things can deadlock. This patch removes the ordered flushes and switches to a best effort filemap_flush like ext4 uses. It's not perfect, but it should fix the deadlocks. Signed-off-by: Chris Mason <clm@fb.com>
2014-06-11Merge branch 'for-linus' of ↵Linus Torvalds1-0/+2
git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs Pull btrfs updates from Chris Mason: "The biggest change here is Josef's rework of the btrfs quota accounting, which improves the in-memory tracking of delayed extent operations. I had been working on Btrfs stack usage for a while, mostly because it had become impossible to do long stress runs with slab, lockdep and pagealloc debugging turned on without blowing the stack. Even though you upgraded us to a nice king sized stack, I kept most of the patches. We also have some very hard to find corruption fixes, an awesome sysfs use after free, and the usual assortment of optimizations, cleanups and other fixes" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: (80 commits) Btrfs: convert smp_mb__{before,after}_clear_bit Btrfs: fix scrub_print_warning to handle skinny metadata extents Btrfs: make fsync work after cloning into a file Btrfs: use right type to get real comparison Btrfs: don't check nodes for extent items Btrfs: don't release invalid page in btrfs_page_exists_in_range() Btrfs: make sure we retry if page is a retriable exception Btrfs: make sure we retry if we couldn't get the page btrfs: replace EINVAL with EOPNOTSUPP for dev_replace raid56 trivial: fs/btrfs/ioctl.c: fix typo s/substract/subtract/ Btrfs: fix leaf corruption after __btrfs_drop_extents Btrfs: ensure btrfs_prev_leaf doesn't miss 1 item Btrfs: fix clone to deal with holes when NO_HOLES feature is enabled btrfs: free delayed node outside of root->inode_lock btrfs: replace EINVAL with ERANGE for resize when ULLONG_MAX Btrfs: fix transaction leak during fsync call btrfs: Avoid trucating page or punching hole in a already existed hole. Btrfs: update commit root on snapshot creation after orphan cleanup Btrfs: ioctl, don't re-lock extent range when not necessary Btrfs: avoid visiting all extent items when cloning a range ...
2014-06-10btrfs: Drop EXTENT_UPTODATE check in hole punching and direct lockingAlex Gartrell1-0/+2
In these instances, we are trying to determine if a page has been accessed since we began the operation for the sake of retry. This is easily accomplished by doing a gang lookup in the page mapping radix tree, and it saves us the dependency on the flag (so that we might eventually delete it). btrfs_page_exists_in_range borrows heavily from find_get_page, replacing the radix tree look up with a gang lookup of 1, so that we can find the next highest page >= index and see if it falls into our lock range. Signed-off-by: Chris Mason <clm@fb.com> Signed-off-by: Alex Gartrell <agartrell@fb.com>