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authorAlex Elder <aelder@sgi.com>2011-07-11 09:51:44 -0500
committerAlex Elder <aelder@sgi.com>2011-07-11 10:21:03 -0500
commitb2ce39740066604288876c752d8170b3b17a21aa (patch)
treefd51670cea52d4c4421ce98a65e8b4979535fb97 /fs/xfs
parent81463b1ca8dbd2f4f180feac3f49c7640e2b5f79 (diff)
Revert "xfs: fix filesystsem freeze race in xfs_trans_alloc"
This reverts commit 7a249cf83da1813cfa71cfe1e265b40045eceb47. That commit created a situation that could lead to a filesystem hang. As Dave Chinner pointed out, xfs_trans_alloc() could hold a reference to m_active_trans (i.e., keep it non-zero) and then wait for SB_FREEZE_TRANS to complete. Meanwhile a filesystem freeze request could set SB_FREEZE_TRANS and then wait for m_active_trans to drop to zero. Nobody benefits from this sequence of events... Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
Diffstat (limited to 'fs/xfs')
-rw-r--r--fs/xfs/xfs_fsops.c2
-rw-r--r--fs/xfs/xfs_iomap.c3
-rw-r--r--fs/xfs/xfs_mount.c14
-rw-r--r--fs/xfs/xfs_trans.c27
-rw-r--r--fs/xfs/xfs_trans.h10
5 files changed, 29 insertions, 27 deletions
diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index b7c492d293b5..9153d2c77caf 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -626,7 +626,7 @@ xfs_fs_log_dummy(
xfs_trans_t *tp;
int error;
- tp = _xfs_trans_alloc(mp, XFS_TRANS_DUMMY1, KM_SLEEP, false);
+ tp = _xfs_trans_alloc(mp, XFS_TRANS_DUMMY1, KM_SLEEP);
error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
XFS_DEFAULT_LOG_COUNT);
if (error) {
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 982b71108f33..091d82b94c4d 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -688,7 +688,8 @@ xfs_iomap_write_unwritten(
* the same inode that we complete here and might deadlock
* on the iolock.
*/
- tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS, true);
+ xfs_wait_for_freeze(mp, SB_FREEZE_TRANS);
+ tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
tp->t_flags |= XFS_TRANS_RESERVE;
error = xfs_trans_reserve(tp, resblks,
XFS_WRITE_LOG_RES(mp), 0,
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 2be5e5cf897a..a19e92381f90 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -1559,9 +1559,15 @@ xfs_fs_writable(xfs_mount_t *mp)
}
/*
+ * xfs_log_sbcount
+ *
* Called either periodically to keep the on disk superblock values
* roughly up to date or from unmount to make sure the values are
* correct on a clean unmount.
+ *
+ * Note this code can be called during the process of freezing, so
+ * we may need to use the transaction allocator which does not not
+ * block when the transaction subsystem is in its frozen state.
*/
int
xfs_log_sbcount(
@@ -1583,13 +1589,7 @@ xfs_log_sbcount(
if (!xfs_sb_version_haslazysbcount(&mp->m_sb))
return 0;
- /*
- * We can be called during the process of freezing, so make sure
- * we go ahead even if the frozen for new transactions. We will
- * always use a sync transaction in the freeze path to make sure
- * the transaction has completed by the time we return.
- */
- tp = _xfs_trans_alloc(mp, XFS_TRANS_SB_COUNT, KM_SLEEP, false);
+ tp = _xfs_trans_alloc(mp, XFS_TRANS_SB_COUNT, KM_SLEEP);
error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
XFS_DEFAULT_LOG_COUNT);
if (error) {
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index 2837220ea5cf..c83f63b33aae 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -566,24 +566,31 @@ xfs_trans_init(
/*
* This routine is called to allocate a transaction structure.
- *
* The type parameter indicates the type of the transaction. These
* are enumerated in xfs_trans.h.
+ *
+ * Dynamically allocate the transaction structure from the transaction
+ * zone, initialize it, and return it to the caller.
*/
-struct xfs_trans *
+xfs_trans_t *
+xfs_trans_alloc(
+ xfs_mount_t *mp,
+ uint type)
+{
+ xfs_wait_for_freeze(mp, SB_FREEZE_TRANS);
+ return _xfs_trans_alloc(mp, type, KM_SLEEP);
+}
+
+xfs_trans_t *
_xfs_trans_alloc(
- struct xfs_mount *mp,
- uint type,
- uint memflags,
- bool wait_for_freeze)
+ xfs_mount_t *mp,
+ uint type,
+ uint memflags)
{
- struct xfs_trans *tp;
+ xfs_trans_t *tp;
atomic_inc(&mp->m_active_trans);
- if (wait_for_freeze)
- xfs_wait_for_freeze(mp, SB_FREEZE_TRANS);
-
tp = kmem_zone_zalloc(xfs_trans_zone, memflags);
tp->t_magic = XFS_TRANS_MAGIC;
tp->t_type = type;
diff --git a/fs/xfs/xfs_trans.h b/fs/xfs/xfs_trans.h
index 4e78432ce143..06a9759b6352 100644
--- a/fs/xfs/xfs_trans.h
+++ b/fs/xfs/xfs_trans.h
@@ -447,14 +447,8 @@ typedef struct xfs_trans {
/*
* XFS transaction mechanism exported interfaces.
*/
-xfs_trans_t *_xfs_trans_alloc(struct xfs_mount *, uint, uint, bool);
-
-static inline struct xfs_trans *
-xfs_trans_alloc(struct xfs_mount *mp, uint type)
-{
- return _xfs_trans_alloc(mp, type, KM_SLEEP, true);
-}
-
+xfs_trans_t *xfs_trans_alloc(struct xfs_mount *, uint);
+xfs_trans_t *_xfs_trans_alloc(struct xfs_mount *, uint, uint);
xfs_trans_t *xfs_trans_dup(xfs_trans_t *);
int xfs_trans_reserve(xfs_trans_t *, uint, uint, uint,
uint, uint);