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authorChristoph Hellwig <hch@lst.de>2011-07-08 14:34:42 +0200
committerChristoph Hellwig <hch@lst.de>2011-07-08 14:34:42 +0200
commit7a249cf83da1813cfa71cfe1e265b40045eceb47 (patch)
tree0c665aad7d32614f7eaa5a11c1b534c8fb5037d3 /fs/xfs/xfs_mount.c
parent33b8f7c2479dfcbc5c27174e44b5f659d9f33c70 (diff)
xfs: fix filesystsem freeze race in xfs_trans_alloc
As pointed out by Jan xfs_trans_alloc can race with a concurrent filesystem freeze when it sleeps during the memory allocation. Fix this by moving the wait_for_freeze call after the memory allocation. This means moving the freeze into the low-level _xfs_trans_alloc helper, which thus grows a new argument. Also fix up some comments in that area while at it. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Alex Elder <aelder@sgi.com> Reviewed-by: Dave Chinner <david@fromorbit.com>
Diffstat (limited to 'fs/xfs/xfs_mount.c')
-rw-r--r--fs/xfs/xfs_mount.c14
1 files changed, 7 insertions, 7 deletions
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index b49b82363d20..63659ee316bd 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -1566,15 +1566,9 @@ 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(
@@ -1596,7 +1590,13 @@ xfs_log_sbcount(
if (!xfs_sb_version_haslazysbcount(&mp->m_sb))
return 0;
- tp = _xfs_trans_alloc(mp, XFS_TRANS_SB_COUNT, KM_SLEEP);
+ /*
+ * 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);
error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
XFS_DEFAULT_LOG_COUNT);
if (error) {