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author | 2016-12-14 22:36:05 -0800 | |
---|---|---|
committer | 2017-02-14 15:50:58 +0100 | |
commit | 4aaedfb0b68ca83471c5f10f1da7f0f4714080a1 (patch) | |
tree | 5b4ad8d821c4bd0618235f15cf68bcd3b558ceb8 /fs/btrfs/inode.c | |
parent | Btrfs: clean up btrfs_ordered_update_i_size (diff) | |
download | linux-4aaedfb0b68ca83471c5f10f1da7f0f4714080a1.tar.gz linux-4aaedfb0b68ca83471c5f10f1da7f0f4714080a1.tar.bz2 linux-4aaedfb0b68ca83471c5f10f1da7f0f4714080a1.zip |
Btrfs: fix another race between truncate and lockless dio write
Dio writes can update i_size in btrfs_get_blocks_direct when it
writes to offset beyond EOF so that endio can update disk_i_size
correctly (because we don't udpate disk_i_size beyond i_size).
However, when truncating down a file, we firstly update i_size
and then wait for in-flight lockless dio reads/writes, according
to the above, i_size may have been changed in dio writes, and
file extents don't get truncated.
For lockless dio writes are always overwrites, i_size is not
supposed to be changed, so this adds a check to filter out this
case.
The race could be reproduced by fstests/generic/299 with patch
"Btrfs: fix btrfs_ordered_update_i_size to update disk_i_size properly"
applied.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/inode.c')
-rw-r--r-- | fs/btrfs/inode.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 29ad99a2e287..70f932d4b69d 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -71,6 +71,7 @@ struct btrfs_dio_data { u64 reserve; u64 unsubmitted_oe_range_start; u64 unsubmitted_oe_range_end; + int overwrite; }; static const struct inode_operations btrfs_dir_inode_operations; @@ -7809,7 +7810,7 @@ unlock: * Need to update the i_size under the extent lock so buffered * readers will get the updated i_size when we unlock. */ - if (start + len > i_size_read(inode)) + if (!dio_data->overwrite && start + len > i_size_read(inode)) i_size_write(inode, start + len); adjust_dio_outstanding_extents(inode, dio_data, len); @@ -8685,6 +8686,7 @@ static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) * not unlock the i_mutex at this case. */ if (offset + count <= inode->i_size) { + dio_data.overwrite = 1; inode_unlock(inode); relock = true; } |