From b2ce39740066604288876c752d8170b3b17a21aa Mon Sep 17 00:00:00 2001 From: Alex Elder Date: Mon, 11 Jul 2011 09:51:44 -0500 Subject: [PATCH] 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 Signed-off-by: Alex Elder --- fs/xfs/xfs_fsops.c | 2 +- fs/xfs/xfs_iomap.c | 3 ++- fs/xfs/xfs_mount.c | 14 +++++++------- fs/xfs/xfs_trans.c | 27 +++++++++++++++++---------- fs/xfs/xfs_trans.h | 10 ++-------- 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); -- GitLab