[PATCH RESEND 0/3] xfs: misc. fixes

[PATCH RESEND 0/3] xfs: misc. fixes

[Brian Foster]

Hi all,

This series includes a few miscellaneous patches I came across while
doing some local branch housekeeping. These have been posted previously
and appear to have fallen through the cracks.

Note that there was an alternative version of patch 3 floating around
somewhere. It doesn't matter much to me which one we take.

Brian

Brian Foster (3):
  xfs: replace on-stack xfs_trans_res with pointer in xfs_create()
  xfs: fix error handling in xfs_qm_log_quotaoff()
  xfs: allow lazy sb counter sync during filesystem freeze sequence

 fs/xfs/xfs_inode.c       | 15 ++++++---------
 fs/xfs/xfs_log.c         |  2 +-
 fs/xfs/xfs_mount.c       | 29 +++++++++++++++++++++--------
 fs/xfs/xfs_mount.h       |  2 +-
 fs/xfs/xfs_qm_syscalls.c | 26 ++++++++++----------------
 5 files changed, 39 insertions(+), 35 deletions(-)

-- 
1.8.3.1

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[PATCH 1/3] xfs: replace on-stack xfs_trans_res with pointer in xfs_create()

[Brian Foster]

There's no need to store a full struct xfs_trans_res on the stack in
xfs_create() and copy the fields. Use a pointer to the appropriate
structures embedded in the xfs_mount.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_inode.c | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 8ed049d..2ffb802 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -1082,7 +1082,7 @@ xfs_create(
 	struct xfs_dquot	*udqp = NULL;
 	struct xfs_dquot	*gdqp = NULL;
 	struct xfs_dquot	*pdqp = NULL;
-	struct xfs_trans_res	tres;
+	struct xfs_trans_res	*tres;
 	uint			resblks;
 
 	trace_xfs_create(dp, name);
@@ -1105,13 +1105,11 @@ xfs_create(
 	if (is_dir) {
 		rdev = 0;
 		resblks = XFS_MKDIR_SPACE_RES(mp, name->len);
-		tres.tr_logres = M_RES(mp)->tr_mkdir.tr_logres;
-		tres.tr_logcount = XFS_MKDIR_LOG_COUNT;
+		tres = &M_RES(mp)->tr_mkdir;
 		tp = xfs_trans_alloc(mp, XFS_TRANS_MKDIR);
 	} else {
 		resblks = XFS_CREATE_SPACE_RES(mp, name->len);
-		tres.tr_logres = M_RES(mp)->tr_create.tr_logres;
-		tres.tr_logcount = XFS_CREATE_LOG_COUNT;
+		tres = &M_RES(mp)->tr_create;
 		tp = xfs_trans_alloc(mp, XFS_TRANS_CREATE);
 	}
 
@@ -1123,17 +1121,16 @@ xfs_create(
 	 * the case we'll drop the one we have and get a more
 	 * appropriate transaction later.
 	 */
-	tres.tr_logflags = XFS_TRANS_PERM_LOG_RES;
-	error = xfs_trans_reserve(tp, &tres, resblks, 0);
+	error = xfs_trans_reserve(tp, tres, resblks, 0);
 	if (error == -ENOSPC) {
 		/* flush outstanding delalloc blocks and retry */
 		xfs_flush_inodes(mp);
-		error = xfs_trans_reserve(tp, &tres, resblks, 0);
+		error = xfs_trans_reserve(tp, tres, resblks, 0);
 	}
 	if (error == -ENOSPC) {
 		/* No space at all so try a "no-allocation" reservation */
 		resblks = 0;
-		error = xfs_trans_reserve(tp, &tres, 0, 0);
+		error = xfs_trans_reserve(tp, tres, 0, 0);
 	}
 	if (error) {
 		cancel_flags = 0;
-- 
1.8.3.1

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[PATCH 2/3] xfs: fix error handling in xfs_qm_log_quotaoff()

[Brian Foster]

The error handling in xfs_qm_log_quotaoff() has a couple problems. If
xfs_trans_commit() fails, we fall through to the error block and call
xfs_trans_cancel(). This is incorrect on commit failure. If
xfs_trans_reserve() fails, we jump to the error block, cancel the tp and
restore the superblock qflags to oldsbqflag. However, oldsbqflag has
been initialized to zero and not yet updated from the original flags so
we set the flags to zero.

Fix up the error handling in xfs_qm_log_quotaoff() to not restore flags
if they haven't been modified and not cancel the tp on commit failure.
Remove the flag restore code altogether because commit error is the only
failure condition and we don't know whether the transaction made it to
disk.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Brian Foster <bfoster@redhat.com>
---
 fs/xfs/xfs_qm_syscalls.c | 26 ++++++++++----------------
 1 file changed, 10 insertions(+), 16 deletions(-)

diff --git a/fs/xfs/xfs_qm_syscalls.c b/fs/xfs/xfs_qm_syscalls.c
index 80f2d77..d1e0ab7 100644
--- a/fs/xfs/xfs_qm_syscalls.c
+++ b/fs/xfs/xfs_qm_syscalls.c
@@ -784,19 +784,21 @@ xfs_qm_log_quotaoff(
 {
 	xfs_trans_t	       *tp;
 	int			error;
-	xfs_qoff_logitem_t     *qoffi=NULL;
-	uint			oldsbqflag=0;
+	xfs_qoff_logitem_t     *qoffi;
+
+	*qoffstartp = NULL;
 
 	tp = xfs_trans_alloc(mp, XFS_TRANS_QM_QUOTAOFF);
 	error = xfs_trans_reserve(tp, &M_RES(mp)->tr_qm_quotaoff, 0, 0);
-	if (error)
-		goto error0;
+	if (error) {
+		xfs_trans_cancel(tp, 0);
+		goto out;
+	}
 
 	qoffi = xfs_trans_get_qoff_item(tp, NULL, flags & XFS_ALL_QUOTA_ACCT);
 	xfs_trans_log_quotaoff_item(tp, qoffi);
 
 	spin_lock(&mp->m_sb_lock);
-	oldsbqflag = mp->m_sb.sb_qflags;
 	mp->m_sb.sb_qflags = (mp->m_qflags & ~(flags)) & XFS_MOUNT_QUOTA_ALL;
 	spin_unlock(&mp->m_sb_lock);
 
@@ -809,19 +811,11 @@ xfs_qm_log_quotaoff(
 	 */
 	xfs_trans_set_sync(tp);
 	error = xfs_trans_commit(tp, 0);
+	if (error)
+		goto out;
 
-error0:
-	if (error) {
-		xfs_trans_cancel(tp, 0);
-		/*
-		 * No one else is modifying sb_qflags, so this is OK.
-		 * We still hold the quotaofflock.
-		 */
-		spin_lock(&mp->m_sb_lock);
-		mp->m_sb.sb_qflags = oldsbqflag;
-		spin_unlock(&mp->m_sb_lock);
-	}
 	*qoffstartp = qoffi;
+out:
 	return error;
 }
 
-- 
1.8.3.1

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[PATCH 3/3] xfs: allow lazy sb counter sync during filesystem freeze sequence

[Brian Foster]

The expectation since the introduction the lazy superblock counters is
that the counters are synced and superblock logged appropriately as part
of the filesystem freeze sequence. This does not occur, however, due to
the logic in xfs_fs_writable() that prevents progress when the fs is in
any state other than SB_UNFROZEN.

While this is a bug, it has not been exposed to date because the last
thing XFS does during freeze is dirty the log. The log recovery process
recalculates the counters from AGI/AGF metadata to ensure everything is
correct. Therefore should a crash occur while an fs is frozen, the
subsequent log recovery puts everything back in order. See the following
commit for reference:

	92821e2b [XFS] Lazy Superblock Counters

We might not always want to rely on dirtying the log on a frozen fs.
Modify xfs_log_sbcount() to proceed when the filesystem is freezing but
not once the freeze process has completed. Modify xfs_fs_writable() to
accept the minimum freeze level for which modifications should be
blocked to support various codepaths.

Signed-off-by: Brian Foster <bfoster@redhat.com>
---
 fs/xfs/xfs_log.c   |  2 +-
 fs/xfs/xfs_mount.c | 29 +++++++++++++++++++++--------
 fs/xfs/xfs_mount.h |  2 +-
 3 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index fe88ef6..e810e9d 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -1031,7 +1031,7 @@ xfs_log_need_covered(xfs_mount_t *mp)
 	struct xlog	*log = mp->m_log;
 	int		needed = 0;
 
-	if (!xfs_fs_writable(mp))
+	if (!xfs_fs_writable(mp, SB_FREEZE_WRITE))
 		return 0;
 
 	if (!xlog_cil_empty(log))
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 51435db..13d1170 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -1074,11 +1074,23 @@ xfs_unmountfs(
 	xfs_sysfs_del(&mp->m_kobj);
 }
 
-int
-xfs_fs_writable(xfs_mount_t *mp)
+/*
+ * Determine whether modifications can proceed. The caller specifies the minimum
+ * freeze level for which modifications should not be allowed. This allows
+ * certain operations to proceed while the freeze sequence is in progress, if
+ * necessary.
+ */
+bool
+xfs_fs_writable(
+	struct xfs_mount	*mp,
+	int			level)
 {
-	return !(mp->m_super->s_writers.frozen || XFS_FORCED_SHUTDOWN(mp) ||
-		(mp->m_flags & XFS_MOUNT_RDONLY));
+	ASSERT(level > SB_UNFROZEN);
+	if ((mp->m_super->s_writers.frozen >= level) ||
+	    XFS_FORCED_SHUTDOWN(mp) || (mp->m_flags & XFS_MOUNT_RDONLY))
+		return false;
+
+	return true;
 }
 
 /*
@@ -1086,9 +1098,9 @@ xfs_fs_writable(xfs_mount_t *mp)
  *
  * Sync the superblock counters to disk.
  *
- * Note this code can be called during the process of freezing, so
- * we may need to use the transaction allocator which does not
- * block when the transaction subsystem is in its frozen state.
+ * Note this code can be called during the process of freezing, so we use the
+ * transaction allocator that does not block when the transaction subsystem is
+ * in its frozen state.
  */
 int
 xfs_log_sbcount(xfs_mount_t *mp)
@@ -1096,7 +1108,8 @@ xfs_log_sbcount(xfs_mount_t *mp)
 	xfs_trans_t	*tp;
 	int		error;
 
-	if (!xfs_fs_writable(mp))
+	/* allow this to proceed during the freeze sequence... */
+	if (!xfs_fs_writable(mp, SB_FREEZE_COMPLETE))
 		return 0;
 
 	xfs_icsb_sync_counters(mp, 0);
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index b0447c8..8852418 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -384,7 +384,7 @@ extern int	xfs_mount_log_sb(xfs_mount_t *, __int64_t);
 extern struct xfs_buf *xfs_getsb(xfs_mount_t *, int);
 extern int	xfs_readsb(xfs_mount_t *, int);
 extern void	xfs_freesb(xfs_mount_t *);
-extern int	xfs_fs_writable(xfs_mount_t *);
+extern bool	xfs_fs_writable(struct xfs_mount *mp, int level);
 extern int	xfs_sb_validate_fsb_count(struct xfs_sb *, __uint64_t);
 
 extern int	xfs_dev_is_read_only(struct xfs_mount *, char *);
-- 
1.8.3.1

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