ML commit c7df4a1ecb8579838ec8c56b2bb6a6716e974f37
Author: Theodore Ts'o <[email protected]>
Date: Mon Nov 11 22:18:13 2019 -0500
ext4: work around deleting a file with i_nlink == 0 safely
If the file system is corrupted such that a file's i_links_count is
too small, then it's possible that when unlinking that file, i_nlink
will already be zero. Previously we were working around this kind of
corruption by forcing i_nlink to one; but we were doing this before
trying to delete the directory entry --- and if the file system is
corrupted enough that ext4_delete_entry() fails, then we exit with
i_nlink elevated, and this causes the orphan inode list handling to be
FUBAR'ed, such that when we unmount the file system, the orphan inode
list can get corrupted.
A better way to fix this is to simply skip trying to call drop_nlink()
if i_nlink is already zero, thus moving the check to the place where
it makes the most sense.
https://bugzilla.kernel.org/show_bug.cgi?id=205433
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Theodore Ts'o <[email protected]>
Cc: [email protected]
Reviewed-by: Andreas Dilger <[email protected]>
[vvs@] taken from RHEl7.9 beta kernel
2020-03-11 Jan Stancek <[email protected]> [3.10.0-1128.el7]
- [fs] ext4: work around deleting a file with i_nlink == 0 safely (Carlos
Maiolino) [1801046]
Signed-off-by: Vasily Averin <[email protected]>
---
fs/ext4/namei.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 24d8617685b1..c8c56ef9281d 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2846,19 +2846,18 @@ static int ext4_unlink(struct inode *dir, struct dentry
*dentry)
if (inode == EXT4_SB(dir->i_sb)->s_balloon_ino)
goto end_unlink;
- if (!inode->i_nlink) {
- ext4_warning(inode->i_sb,
- "Deleting nonexistent file (%lu), %d",
- inode->i_ino, inode->i_nlink);
- set_nlink(inode, 1);
- }
retval = ext4_delete_entry(handle, dir, de, bh);
if (retval)
goto end_unlink;
dir->i_ctime = dir->i_mtime = ext4_current_time(dir);
ext4_update_dx_flag(dir);
ext4_mark_inode_dirty(handle, dir);
- drop_nlink(inode);
+ if (inode->i_nlink == 0)
+ ext4_warning(inode->i_sb,
+ "Deleting nonexistent file (%lu), %d",
+ inode->i_ino, inode->i_nlink);
+ else
+ drop_nlink(inode);
if (!inode->i_nlink)
ext4_orphan_add(handle, inode);
inode->i_ctime = ext4_current_time(inode);
--
2.17.1
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