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authorTheodore Ts'o <tytso@mit.edu>2019-11-11 22:18:13 -0500
committerTheodore Ts'o <tytso@mit.edu>2019-11-19 12:25:21 -0500
commitc7df4a1ecb8579838ec8c56b2bb6a6716e974f37 (patch)
tree7a66ced22f28d23c280b84e42f9a595886236456 /fs/ext4
parent4ea99936a1630f51fc3a2d61a58ec4a1c4b7d55a (diff)
downloadlinux-c7df4a1ecb8579838ec8c56b2bb6a6716e974f37.tar.bz2
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/20191112032903.8828-1-tytso@mit.edu Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@kernel.org Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/namei.c11
1 files changed, 5 insertions, 6 deletions
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index a67cae3c8ff5..a856997d87b5 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -3196,18 +3196,17 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
if (IS_DIRSYNC(dir))
ext4_handle_sync(handle);
- if (inode->i_nlink == 0) {
- ext4_warning_inode(inode, "Deleting file '%.*s' with no links",
- dentry->d_name.len, dentry->d_name.name);
- set_nlink(inode, 1);
- }
retval = ext4_delete_entry(handle, dir, de, bh);
if (retval)
goto end_unlink;
dir->i_ctime = dir->i_mtime = 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(inode, "Deleting file '%.*s' with no links",
+ dentry->d_name.len, dentry->d_name.name);
+ else
+ drop_nlink(inode);
if (!inode->i_nlink)
ext4_orphan_add(handle, inode);
inode->i_ctime = current_time(inode);