[PATCH V13 05/16] xfs: Check for extent overflow when removing dir entries
From: Chandan Babu R <hidden>
Date: 2021-01-10 03:31:03
Subsystem:
filesystems (vfs and infrastructure), the rest, xfs filesystem · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds, Carlos Maiolino
Directory entry removal must always succeed; Hence XFS does the following during low disk space scenario: 1. Data/Free blocks linger until a future remove operation. 2. Dabtree blocks would be swapped with the last block in the leaf space and then the new last block will be unmapped. This facility is reused during low inode extent count scenario i.e. this commit causes xfs_bmap_del_extent_real() to return -ENOSPC error code so that the above mentioned behaviour is exercised causing no change to the directory's extent count. Signed-off-by: Chandan Babu R <redacted> --- fs/xfs/libxfs/xfs_bmap.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)
diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 32aeacf6f055..94063ac1d085 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c@@ -5151,6 +5151,23 @@ xfs_bmap_del_extent_real( /* * Deleting the middle of the extent. */ + + /* + * For directories, -ENOSPC is returned since a directory entry + * remove operation must not fail due to low extent count + * availability. -ENOSPC will be handled by higher layers of XFS + * by letting the corresponding empty Data/Free blocks to linger + * until a future remove operation. Dabtree blocks would be + * swapped with the last block in the leaf space and then the + * new last block will be unmapped. + */ + error = xfs_iext_count_may_overflow(ip, whichfork, 1); + if (error == -ENOSPC) { + ASSERT(S_ISDIR(VFS_I(ip)->i_mode) && + whichfork == XFS_DATA_FORK); + goto done; + } + old = got; got.br_blockcount = del->br_startoff - got.br_startoff;
--
2.29.2