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[v16,01/28] xfsprogs: fix an ABBA deadlock in xfs_rename

Message ID 20210326003131.32642-2-allison.henderson@oracle.com (mailing list archive)
State New
Headers show
Series xfsprogs: Delay Ready Attributes | expand

Commit Message

Allison Henderson March 26, 2021, 12:31 a.m. UTC
From: "Darrick J. Wong" <darrick.wong@oracle.com>

Source kernel commit: 6da1b4b1ab36d80a3994fd4811c8381de10af604

When overlayfs is running on top of xfs and the user unlinks a file in
the overlay, overlayfs will create a whiteout inode and ask xfs to
"rename" the whiteout file atop the one being unlinked.  If the file
being unlinked loses its one nlink, we then have to put the inode on the
unlinked list.

This requires us to grab the AGI buffer of the whiteout inode to take it
off the unlinked list (which is where whiteouts are created) and to grab
the AGI buffer of the file being deleted.  If the whiteout was created
in a higher numbered AG than the file being deleted, we'll lock the AGIs
in the wrong order and deadlock.

Therefore, grab all the AGI locks we think we'll need ahead of time, and
in order of increasing AG number per the locking rules.

Reported-by: wenli xie <wlxie7296@gmail.com>
Fixes: 93597ae8dac0 ("xfs: Fix deadlock between AGI and AGF when target_ip exists in xfs_rename()")
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
 libxfs/xfs_dir2.h    | 2 --
 libxfs/xfs_dir2_sf.c | 2 +-
 2 files changed, 1 insertion(+), 3 deletions(-)
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diff --git a/libxfs/xfs_dir2.h b/libxfs/xfs_dir2.h
index e553786..d03e609 100644
--- a/libxfs/xfs_dir2.h
+++ b/libxfs/xfs_dir2.h
@@ -47,8 +47,6 @@  extern int xfs_dir_lookup(struct xfs_trans *tp, struct xfs_inode *dp,
 extern int xfs_dir_removename(struct xfs_trans *tp, struct xfs_inode *dp,
 				struct xfs_name *name, xfs_ino_t ino,
 				xfs_extlen_t tot);
-extern bool xfs_dir2_sf_replace_needblock(struct xfs_inode *dp,
-				xfs_ino_t inum);
 extern int xfs_dir_replace(struct xfs_trans *tp, struct xfs_inode *dp,
 				struct xfs_name *name, xfs_ino_t inum,
 				xfs_extlen_t tot);
diff --git a/libxfs/xfs_dir2_sf.c b/libxfs/xfs_dir2_sf.c
index fbbb638..e5a8e0c 100644
--- a/libxfs/xfs_dir2_sf.c
+++ b/libxfs/xfs_dir2_sf.c
@@ -1018,7 +1018,7 @@  xfs_dir2_sf_removename(
  * Check whether the sf dir replace operation need more blocks.
+static bool
 	struct xfs_inode	*dp,
 	xfs_ino_t		inum)