On 1/20/12 2:34 PM, Jan Kara wrote: > m_active_trans counter is racy wrt filesystem freezing. The patch replaces it > with generic counter of running transactions which is properly synchronized > with filesystem freezing. Things are a bit more complex because we need to log > a dummy transaction and free block counters after the filesystem is frozen so > we need to pass information to _xfs_trans_alloc() whether the transaction is > part of filesystem freezing or not. Here's the version I have which will get me past xfstest 068 and avoids some warnings. This version brings the sb_start_write go/nogo flag up to xfs_log_sbcount() to avoid a warning at unmount time. I'd still like to make some of the variable/macro naming more obvious but this might do for now. diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c index 1c6fdeb..503fdfa 100644 --- a/fs/xfs/xfs_fsops.c +++ b/fs/xfs/xfs_fsops.c @@ -645,12 +645,13 @@ out: */ int xfs_fs_log_dummy( - xfs_mount_t *mp) + xfs_mount_t *mp, + bool for_freeze) { 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, for_freeze); 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_fsops.h b/fs/xfs/xfs_fsops.h index 1b6a98b..4d6253e 100644 --- a/fs/xfs/xfs_fsops.h +++ b/fs/xfs/xfs_fsops.h @@ -25,6 +25,6 @@ extern int xfs_fs_counts(xfs_mount_t *mp, xfs_fsop_counts_t *cnt); extern int xfs_reserve_blocks(xfs_mount_t *mp, __uint64_t *inval, xfs_fsop_resblks_t *outval); extern int xfs_fs_goingdown(xfs_mount_t *mp, __uint32_t inflags); -extern int xfs_fs_log_dummy(struct xfs_mount *mp); +extern int xfs_fs_log_dummy(struct xfs_mount *mp, bool for_freeze); #endif /* __XFS_FSOPS_H__ */ diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index 246c7d5..99f4e42 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -679,8 +679,8 @@ 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, XFS_HONOR_FREEZE_TRANS); tp->t_flags |= XFS_TRANS_RESERVE; error = xfs_trans_reserve(tp, resblks, XFS_WRITE_LOG_RES(mp), 0, diff --git a/fs/xfs/xfs_linux.h b/fs/xfs/xfs_linux.h index 828662f..b2731ea 100644 --- a/fs/xfs/xfs_linux.h +++ b/fs/xfs/xfs_linux.h @@ -308,4 +308,7 @@ static inline __uint64_t howmany_64(__uint64_t x, __uint32_t y) #endif /* DEBUG */ +#define XFS_HONOR_FREEZE_TRANS false +#define XFS_IGNORE_FREEZE_TRANS true + #endif /* __XFS_LINUX__ */ diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c index d06afbc..663bc96 100644 --- a/fs/xfs/xfs_mount.c +++ b/fs/xfs/xfs_mount.c @@ -1513,7 +1513,7 @@ xfs_unmountfs( xfs_warn(mp, "Unable to free reserved block pool. " "Freespace may not be correct on next mount."); - error = xfs_log_sbcount(mp); + error = xfs_log_sbcount(mp, XFS_HONOR_FREEZE_TRANS); if (error) xfs_warn(mp, "Unable to update superblock counters. " "Freespace may not be correct on next mount."); @@ -1555,7 +1555,7 @@ xfs_fs_writable(xfs_mount_t *mp) * block when the transaction subsystem is in its frozen state. */ int -xfs_log_sbcount(xfs_mount_t *mp) +xfs_log_sbcount(xfs_mount_t *mp, int freezing) { xfs_trans_t *tp; int error; @@ -1572,7 +1572,7 @@ xfs_log_sbcount(xfs_mount_t *mp) if (!xfs_sb_version_haslazysbcount(&mp->m_sb)) return 0; - tp = _xfs_trans_alloc(mp, XFS_TRANS_SB_COUNT, KM_SLEEP); + tp = _xfs_trans_alloc(mp, XFS_TRANS_SB_COUNT, KM_SLEEP, freezing); 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_mount.h b/fs/xfs/xfs_mount.h index 19f69e2..9319047 100644 --- a/fs/xfs/xfs_mount.h +++ b/fs/xfs/xfs_mount.h @@ -195,7 +195,6 @@ typedef struct xfs_mount { uint m_chsize; /* size of next field */ struct xfs_chash *m_chash; /* fs private inode per-cluster * hash table */ - atomic_t m_active_trans; /* number trans frozen */ #ifdef HAVE_PERCPU_SB xfs_icsb_cnts_t __percpu *m_sb_cnts; /* per-cpu superblock counters */ unsigned long m_icsb_counters; /* disabled per-cpu counters */ @@ -311,7 +310,6 @@ void xfs_do_force_shutdown(struct xfs_mount *mp, int flags, char *fname, #define SHUTDOWN_DEVICE_REQ 0x0020 /* failed all paths to the device */ #define xfs_test_for_freeze(mp) ((mp)->m_super->s_frozen) -#define xfs_wait_for_freeze(mp,l) vfs_check_frozen((mp)->m_super, (l)) /* * Flags for xfs_mountfs @@ -370,7 +368,7 @@ typedef struct xfs_mod_sb { int64_t msb_delta; /* Change to make to specified field */ } xfs_mod_sb_t; -extern int xfs_log_sbcount(xfs_mount_t *); +extern int xfs_log_sbcount(xfs_mount_t *, int); extern __uint64_t xfs_default_resblks(xfs_mount_t *mp); extern int xfs_mountfs(xfs_mount_t *mp); diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c index ee5b695..a257077 100644 --- a/fs/xfs/xfs_super.c +++ b/fs/xfs/xfs_super.c @@ -1198,7 +1198,7 @@ xfs_fs_freeze( xfs_save_resvblks(mp); xfs_quiesce_attr(mp); - return -xfs_fs_log_dummy(mp); + return -xfs_fs_log_dummy(mp, XFS_IGNORE_FREEZE_TRANS); } STATIC int @@ -1285,7 +1285,6 @@ xfs_fs_fill_super( spin_lock_init(&mp->m_sb_lock); mutex_init(&mp->m_growlock); - atomic_set(&mp->m_active_trans, 0); mp->m_super = sb; sb->s_fs_info = mp; diff --git a/fs/xfs/xfs_sync.c b/fs/xfs/xfs_sync.c index 40b75ee..b9a6be0 100644 --- a/fs/xfs/xfs_sync.c +++ b/fs/xfs/xfs_sync.c @@ -406,7 +406,7 @@ xfs_quiesce_data( /* mark the log as covered if needed */ if (xfs_log_need_covered(mp)) - error2 = xfs_fs_log_dummy(mp); + error2 = xfs_fs_log_dummy(mp, XFS_HONOR_FREEZE_TRANS); /* flush data-only devices */ if (mp->m_rtdev_targp) @@ -454,20 +454,13 @@ xfs_quiesce_attr( int error = 0; /* wait for all modifications to complete */ - while (atomic_read(&mp->m_active_trans) > 0) - delay(100); + sb_wait_write(mp->m_super, SB_FREEZE_TRANS); /* flush inodes and push all remaining buffers out to disk */ xfs_quiesce_fs(mp); - /* - * Just warn here till VFS can correctly support - * read-only remount without racing. - */ - WARN_ON(atomic_read(&mp->m_active_trans) != 0); - /* Push the superblock and write an unmount record */ - error = xfs_log_sbcount(mp); + error = xfs_log_sbcount(mp, XFS_IGNORE_FREEZE_TRANS); if (error) xfs_warn(mp, "xfs_attr_quiesce: failed to log sb changes. " "Frozen image may not be consistent."); @@ -500,7 +493,7 @@ xfs_sync_worker( /* dgc: errors ignored here */ if (mp->m_super->s_frozen == SB_UNFROZEN && xfs_log_need_covered(mp)) - error = xfs_fs_log_dummy(mp); + error = xfs_fs_log_dummy(mp, XFS_HONOR_FREEZE_TRANS); else xfs_log_force(mp, 0); diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c index 329b06a..dda8877 100644 --- a/fs/xfs/xfs_trans.c +++ b/fs/xfs/xfs_trans.c @@ -577,24 +577,28 @@ 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); + return _xfs_trans_alloc(mp, type, KM_SLEEP, XFS_HONOR_FREEZE_TRANS); } xfs_trans_t * _xfs_trans_alloc( xfs_mount_t *mp, uint type, - uint memflags) + uint memflags, + bool freezing) { xfs_trans_t *tp; - atomic_inc(&mp->m_active_trans); - + if (!freezing) + sb_start_write(mp->m_super, SB_FREEZE_TRANS); + else + WARN_ON(xfs_test_for_freeze(mp) != SB_FREEZE_TRANS); tp = kmem_zone_zalloc(xfs_trans_zone, memflags); tp->t_magic = XFS_TRANS_MAGIC; tp->t_type = type; tp->t_mountp = mp; + if (freezing) + tp->t_flags |= XFS_TRANS_FREEZING; INIT_LIST_HEAD(&tp->t_items); INIT_LIST_HEAD(&tp->t_busy); return tp; @@ -611,7 +615,8 @@ xfs_trans_free( xfs_alloc_busy_sort(&tp->t_busy); xfs_alloc_busy_clear(tp->t_mountp, &tp->t_busy, false); - atomic_dec(&tp->t_mountp->m_active_trans); + if (!(tp->t_flags & XFS_TRANS_FREEZING)) + sb_end_write(tp->t_mountp->m_super, SB_FREEZE_TRANS); xfs_trans_free_dqinfo(tp); kmem_zone_free(xfs_trans_zone, tp); } @@ -654,7 +659,10 @@ xfs_trans_dup( xfs_trans_dup_dqinfo(tp, ntp); - atomic_inc(&tp->t_mountp->m_active_trans); + if (tp->t_flags & XFS_TRANS_FREEZING) + ntp->t_flags |= XFS_TRANS_FREEZING; + else + sb_dup_write(tp->t_mountp->m_super, SB_FREEZE_TRANS); return ntp; } diff --git a/fs/xfs/xfs_trans.h b/fs/xfs/xfs_trans.h index f611870..cae91db 100644 --- a/fs/xfs/xfs_trans.h +++ b/fs/xfs/xfs_trans.h @@ -179,6 +179,7 @@ struct xfs_log_item_desc { #define XFS_TRANS_SYNC 0x08 /* make commit synchronous */ #define XFS_TRANS_DQ_DIRTY 0x10 /* at least one dquot in trx dirty */ #define XFS_TRANS_RESERVE 0x20 /* OK to use reserved data blocks */ +#define XFS_TRANS_FREEZING 0x40 /* can happen on frozen filesystem */ /* * Values for call flags parameter. @@ -447,7 +448,7 @@ 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); xfs_trans_t *xfs_trans_dup(xfs_trans_t *); int xfs_trans_reserve(xfs_trans_t *, uint, uint, uint, uint, uint); -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html