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xfs: reload the last iunlink item 

It turns out that there are some serious bugs in how xfs handles the
 unlinked inode lists.  Way back before 4.14, there was a bug where a ro
 mount of a dirty filesystem would recover the log bug neglect to purge
 the unlinked list.  This leads to clean unmounted filesystems with
 unlinked inodes.  Starting around 5.15, we also converted the codebase
 to maintain a doubly-linked incore unlinked list.  However, we never
 provided the ability to load the incore list from disk.  If someone
 tries to allocate an O_TMPFILE file on a clean fs with a pre-existing
 unlinked list or even deletes a file, the code will fail and the fs
 shuts down.
 
 This first part of the correction effort adds the ability to load the
 first inode in the bucket when unlinking a file; and to load the next
 inode in the list when inactivating (freeing) an inode.
 
 This has been lightly tested with fstests.  Enjoy!
 
 Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Merge tag 'fix-iunlink-6.6_2023-09-12' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-6.6-fixesA

xfs: reload the last iunlink item

It turns out that there are some serious bugs in how xfs handles the
unlinked inode lists.  Way back before 4.14, there was a bug where a ro
mount of a dirty filesystem would recover the log bug neglect to purge
the unlinked list.  This leads to clean unmounted filesystems with
unlinked inodes.  Starting around 5.15, we also converted the codebase
to maintain a doubly-linked incore unlinked list.  However, we never
provided the ability to load the incore list from disk.  If someone
tries to allocate an O_TMPFILE file on a clean fs with a pre-existing
unlinked list or even deletes a file, the code will fail and the fs
shuts down.

This first part of the correction effort adds the ability to load the
first inode in the bucket when unlinking a file; and to load the next
inode in the list when inactivating (freeing) an inode.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

* tag 'fix-iunlink-6.6_2023-09-12' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
  xfs: load uncached unlinked inodes into memory on demand
This commit is contained in:
Chandan Babu R 2023-09-13 10:25:00 +05:30
parent b6c2b6378d 68b957f64f
commit fffcdcc31f
2 changed files with 100 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

80
fs/xfs/xfs_inode.c
View File

@ -1828,12 +1828,17 @@ xfs_iunlink_lookup(
rcu_read_lock();
ip = radix_tree_lookup(&pag->pag_ici_root, agino);
if (!ip) {
/* Caller can handle inode not being in memory. */
rcu_read_unlock();
return NULL;
}
/*
* Inode not in memory or in RCU freeing limbo should not happen.
* Warn about this and let the caller handle the failure.
* Inode in RCU freeing limbo should not happen. Warn about this and
* let the caller handle the failure.
*/
if (WARN_ON_ONCE(!ip || !ip->i_ino)) {
if (WARN_ON_ONCE(!ip->i_ino)) {
rcu_read_unlock();
return NULL;
}
@ -1842,7 +1847,10 @@ xfs_iunlink_lookup(
return ip;
}
/* Update the prev pointer of the next agino. */
/*
* Update the prev pointer of the next agino. Returns -ENOLINK if the inode
* is not in cache.
*/
static int
xfs_iunlink_update_backref(
struct xfs_perag *pag,
@ -1857,7 +1865,8 @@ xfs_iunlink_update_backref(
ip = xfs_iunlink_lookup(pag, next_agino);
if (!ip)
return -EFSCORRUPTED;
return -ENOLINK;
ip->i_prev_unlinked = prev_agino;
return 0;
}
@ -1901,6 +1910,62 @@ xfs_iunlink_update_bucket(
return 0;
}
/*
* Load the inode @next_agino into the cache and set its prev_unlinked pointer
* to @prev_agino. Caller must hold the AGI to synchronize with other changes
* to the unlinked list.
*/
STATIC int
xfs_iunlink_reload_next(
struct xfs_trans *tp,
struct xfs_buf *agibp,
xfs_agino_t prev_agino,
xfs_agino_t next_agino)
{
struct xfs_perag *pag = agibp->b_pag;
struct xfs_mount *mp = pag->pag_mount;
struct xfs_inode *next_ip = NULL;
xfs_ino_t ino;
int error;
ASSERT(next_agino != NULLAGINO);
#ifdef DEBUG
rcu_read_lock();
next_ip = radix_tree_lookup(&pag->pag_ici_root, next_agino);
ASSERT(next_ip == NULL);
rcu_read_unlock();
#endif
xfs_info_ratelimited(mp,
"Found unrecovered unlinked inode 0x%x in AG 0x%x. Initiating recovery.",
next_agino, pag->pag_agno);
/*
* Use an untrusted lookup just to be cautious in case the AGI has been
* corrupted and now points at a free inode. That shouldn't happen,
* but we'd rather shut down now since we're already running in a weird
* situation.
*/
ino = XFS_AGINO_TO_INO(mp, pag->pag_agno, next_agino);
error = xfs_iget(mp, tp, ino, XFS_IGET_UNTRUSTED, 0, &next_ip);
if (error)
return error;
/* If this is not an unlinked inode, something is very wrong. */
if (VFS_I(next_ip)->i_nlink != 0) {
error = -EFSCORRUPTED;
goto rele;
}
next_ip->i_prev_unlinked = prev_agino;
trace_xfs_iunlink_reload_next(next_ip);
rele:
ASSERT(!(VFS_I(next_ip)->i_state & I_DONTCACHE));
xfs_irele(next_ip);
return error;
}
static int
xfs_iunlink_insert_inode(
struct xfs_trans *tp,
@ -1932,6 +1997,8 @@ xfs_iunlink_insert_inode(
* inode.
*/
error = xfs_iunlink_update_backref(pag, agino, next_agino);
if (error == -ENOLINK)
error = xfs_iunlink_reload_next(tp, agibp, agino, next_agino);
if (error)
return error;
@ -2026,6 +2093,9 @@ xfs_iunlink_remove_inode(
*/
error = xfs_iunlink_update_backref(pag, ip->i_prev_unlinked,
ip->i_next_unlinked);
if (error == -ENOLINK)
error = xfs_iunlink_reload_next(tp, agibp, ip->i_prev_unlinked,
ip->i_next_unlinked);
if (error)
return error;

25
fs/xfs/xfs_trace.h
View File

@ -3824,6 +3824,31 @@ TRACE_EVENT(xfs_iunlink_update_dinode,
__entry->new_ptr)
);
TRACE_EVENT(xfs_iunlink_reload_next,
TP_PROTO(struct xfs_inode *ip),
TP_ARGS(ip),
TP_STRUCT__entry(
__field(dev_t, dev)
__field(xfs_agnumber_t, agno)
__field(xfs_agino_t, agino)
__field(xfs_agino_t, prev_agino)
__field(xfs_agino_t, next_agino)
),
TP_fast_assign(
__entry->dev = ip->i_mount->m_super->s_dev;
__entry->agno = XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino);
__entry->agino = XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino);
__entry->prev_agino = ip->i_prev_unlinked;
__entry->next_agino = ip->i_next_unlinked;
),
TP_printk("dev %d:%d agno 0x%x agino 0x%x prev_unlinked 0x%x next_unlinked 0x%x",
MAJOR(__entry->dev), MINOR(__entry->dev),
__entry->agno,
__entry->agino,
__entry->prev_agino,
__entry->next_agino)
);
DECLARE_EVENT_CLASS(xfs_ag_inode_class,
TP_PROTO(struct xfs_inode *ip),
TP_ARGS(ip),