From 7a249cf83da1813cfa71cfe1e265b40045eceb47 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Fri, 8 Jul 2011 14:34:42 +0200 Subject: [PATCH] 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 Reviewed-by: Alex Elder Reviewed-by: Dave Chinner --- 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, 27 insertions(+), 29 deletions(-) diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c index 9153d2c77caf..b7c492d293b5 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); + tp = _xfs_trans_alloc(mp, XFS_TRANS_DUMMY1, KM_SLEEP, false); 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 091d82b94c4d..982b71108f33 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -688,8 +688,7 @@ xfs_iomap_write_unwritten( * the same inode that we complete here and might deadlock * on the iolock. */ - xfs_wait_for_freeze(mp, SB_FREEZE_TRANS); - tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS); + tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS, true); 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 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) { diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c index c83f63b33aae..2837220ea5cf 100644 --- a/fs/xfs/xfs_trans.c +++ b/fs/xfs/xfs_trans.c @@ -566,31 +566,24 @@ 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. */ -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 * +struct xfs_trans * _xfs_trans_alloc( - xfs_mount_t *mp, - uint type, - uint memflags) + struct xfs_mount *mp, + uint type, + uint memflags, + bool wait_for_freeze) { - xfs_trans_t *tp; + struct xfs_trans *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 06a9759b6352..4e78432ce143 100644 --- a/fs/xfs/xfs_trans.h +++ b/fs/xfs/xfs_trans.h @@ -447,8 +447,14 @@ typedef struct xfs_trans { /* * XFS transaction mechanism exported interfaces. */ -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_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_dup(xfs_trans_t *); int xfs_trans_reserve(xfs_trans_t *, uint, uint, uint, uint, uint); -- 2.20.1