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6 Commits
| Author | SHA1 | Message | Date | |
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Filipe Manana
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e289f03ea7 |
btrfs: fix corrupt log due to concurrent fsync of inodes with shared extents
When we have extents shared amongst different inodes in the same subvolume, if we fsync them in parallel we can end up with checksum items in the log tree that represent ranges which overlap. For example, consider we have inodes A and B, both sharing an extent that covers the logical range from X to X + 64KiB: 1) Task A starts an fsync on inode A; 2) Task B starts an fsync on inode B; 3) Task A calls btrfs_csum_file_blocks(), and the first search in the log tree, through btrfs_lookup_csum(), returns -EFBIG because it finds an existing checksum item that covers the range from X - 64KiB to X; 4) Task A checks that the checksum item has not reached the maximum possible size (MAX_CSUM_ITEMS) and then releases the search path before it does another path search for insertion (through a direct call to btrfs_search_slot()); 5) As soon as task A releases the path and before it does the search for insertion, task B calls btrfs_csum_file_blocks() and gets -EFBIG too, because there is an existing checksum item that has an end offset that matches the start offset (X) of the checksum range we want to log; 6) Task B releases the path; 7) Task A does the path search for insertion (through btrfs_search_slot()) and then verifies that the checksum item that ends at offset X still exists and extends its size to insert the checksums for the range from X to X + 64KiB; 8) Task A releases the path and returns from btrfs_csum_file_blocks(), having inserted the checksums into an existing checksum item that got its size extended. At this point we have one checksum item in the log tree that covers the logical range from X - 64KiB to X + 64KiB; 9) Task B now does a search for insertion using btrfs_search_slot() too, but it finds that the previous checksum item no longer ends at the offset X, it now ends at an of offset X + 64KiB, so it leaves that item untouched. Then it releases the path and calls btrfs_insert_empty_item() that inserts a checksum item with a key offset corresponding to X and a size for inserting a single checksum (4 bytes in case of crc32c). Subsequent iterations end up extending this new checksum item so that it contains the checksums for the range from X to X + 64KiB. So after task B returns from btrfs_csum_file_blocks() we end up with two checksum items in the log tree that have overlapping ranges, one for the range from X - 64KiB to X + 64KiB, and another for the range from X to X + 64KiB. Having checksum items that represent ranges which overlap, regardless of being in the log tree or in the chekcsums tree, can lead to problems where checksums for a file range end up not being found. This type of problem has happened a few times in the past and the following commits fixed them and explain in detail why having checksum items with overlapping ranges is problematic: |
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Nikolay Borisov
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fe119a6eeb |
btrfs: switch to per-transaction pinned extents
This commit flips the switch to start tracking/processing pinned extents on a per-transaction basis. It mostly replaces all references from btrfs_fs_info::(pinned_extents|freed_extents[]) to btrfs_transaction::pinned_extents. Two notable modifications that warrant explicit mention are changing clean_pinned_extents to get a reference to the previously running transaction. The other one is removal of call to btrfs_destroy_pinned_extent since transactions are going to be cleaned in btrfs_cleanup_one_transaction. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Josef Bacik
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41a2ee75aa |
btrfs: introduce per-inode file extent tree
In order to keep track of where we have file extents on disk, and thus where it is safe to adjust the i_size to, we need to have a tree in place to keep track of the contiguous areas we have file extents for. Add helpers to use this tree, as it's not required for NO_HOLES file systems. We will use this by setting DIRTY for areas we know we have file extent item's set, and clearing it when we remove file extent items for truncation. Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Josef Bacik
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b3f167aa6c |
btrfs: move the failrec tree stuff into extent-io-tree.h
This needs to be cleaned up in the future, but for now it belongs to the extent-io-tree stuff since it uses the internal tree search code. Needed to export get_state_failrec and set_state_failrec as well since we're not going to move the actual IO part of the failrec stuff out at this point. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Josef Bacik
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083e75e7e6 |
btrfs: export find_delalloc_range
This utilizes internal stuff to the extent_io_tree, so we need to export it before we move it. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Josef Bacik
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9c7d3a5483 |
btrfs: move extent_io_tree defs to their own header
extent_io.c/h are huge, encompassing a bunch of different things. The extent_io_tree code can live on its own, so separate this out. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |