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authorBrian Foster <bfoster@redhat.com>2015-05-29 08:14:55 +1000
committerDave Chinner <david@fromorbit.com>2015-05-29 08:14:55 +1000
commit22419ac9fe5e79483596cebdbd1d1209c18bac1a (patch)
tree334293b6a6b987030c9cc5c7a7af9d3bf486ab8c /fs
parentcddc116228cb9d51d3224d23ba3e61fbbc3ec3d2 (diff)
downloadkernel-22419ac9fe5e79483596cebdbd1d1209c18bac1a.tar.gz
xfs: fix broken i_nlink accounting for whiteout tmpfile inode
XFS uses the internal tmpfile() infrastructure for the whiteout inode used for RENAME_WHITEOUT operations. For tmpfile inodes, XFS allocates the inode, drops di_nlink, adds the inode to the agi unlinked list, calls d_tmpfile() which correspondingly drops i_nlink of the vfs inode, and then finishes the common inode setup (e.g., clear I_NEW and unlock). The d_tmpfile() call was originally made inxfs_create_tmpfile(), but was pulled up out of that function as part of the following commit to resolve a deadlock issue: 330033d6 xfs: fix tmpfile/selinux deadlock and initialize security As a result, callers of xfs_create_tmpfile() are responsible for either calling d_tmpfile() or fixing up i_nlink appropriately. The whiteout tmpfile allocation helper does neither. As a result, the vfs ->i_nlink becomes inconsistent with the on-disk ->di_nlink once xfs_rename() links it back into the source dentry and calls xfs_bumplink(). Update the assert in xfs_rename() to help detect this problem in the future and update xfs_rename_alloc_whiteout() to decrement the link count as part of the manual tmpfile inode setup. Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/xfs/xfs_inode.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 1117dd3ba123..539a85fddbc2 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -2879,7 +2879,13 @@ xfs_rename_alloc_whiteout(
if (error)
return error;
- /* Satisfy xfs_bumplink that this is a real tmpfile */
+ /*
+ * Prepare the tmpfile inode as if it were created through the VFS.
+ * Otherwise, the link increment paths will complain about nlink 0->1.
+ * Drop the link count as done by d_tmpfile(), complete the inode setup
+ * and flag it as linkable.
+ */
+ drop_nlink(VFS_I(tmpfile));
xfs_finish_inode_setup(tmpfile);
VFS_I(tmpfile)->i_state |= I_LINKABLE;
@@ -3147,7 +3153,7 @@ xfs_rename(
* intermediate state on disk.
*/
if (wip) {
- ASSERT(wip->i_d.di_nlink == 0);
+ ASSERT(VFS_I(wip)->i_nlink == 0 && wip->i_d.di_nlink == 0);
error = xfs_bumplink(tp, wip);
if (error)
goto out_trans_abort;