From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Theodore Ts'o <tytso@mit.edu>,
stable@kernel.org, Andreas Dilger <adilger@dilger.ca>,
Sasha Levin <sashal@kernel.org>,
linux-ext4@vger.kernel.org
Subject: [PATCH AUTOSEL 4.9 31/42] ext4: work around deleting a file with i_nlink == 0 safely
Date: Wed, 11 Dec 2019 10:34:59 -0500 [thread overview]
Message-ID: <20191211153510.23861-31-sashal@kernel.org> (raw)
In-Reply-To: <20191211153510.23861-1-sashal@kernel.org>
From: Theodore Ts'o <tytso@mit.edu>
[ Upstream commit c7df4a1ecb8579838ec8c56b2bb6a6716e974f37 ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/ext4/namei.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 29dc02758a52b..b8082ca9e3bac 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -3078,18 +3078,17 @@ 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 = 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(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 = ext4_current_time(inode);
--
2.20.1
prev parent reply other threads:[~2019-12-11 15:35 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20191211153510.23861-1-sashal@kernel.org>
2019-12-11 15:34 ` [PATCH AUTOSEL 4.9 14/42] jbd2: Fix statistics for the number of logged blocks Sasha Levin
2019-12-11 15:34 ` [PATCH AUTOSEL 4.9 29/42] ext4: fix a bug in ext4_wait_for_tail_page_commit Sasha Levin
2019-12-11 15:34 ` Sasha Levin [this message]
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