Commit 7a249cf8 authored by Christoph Hellwig's avatar Christoph Hellwig

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: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarAlex Elder <aelder@sgi.com>
Reviewed-by: default avatarDave Chinner <david@fromorbit.com>
parent 33b8f7c2
...@@ -626,7 +626,7 @@ xfs_fs_log_dummy( ...@@ -626,7 +626,7 @@ xfs_fs_log_dummy(
xfs_trans_t *tp; xfs_trans_t *tp;
int error; 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, error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
XFS_DEFAULT_LOG_COUNT); XFS_DEFAULT_LOG_COUNT);
if (error) { if (error) {
......
...@@ -688,8 +688,7 @@ xfs_iomap_write_unwritten( ...@@ -688,8 +688,7 @@ xfs_iomap_write_unwritten(
* the same inode that we complete here and might deadlock * the same inode that we complete here and might deadlock
* on the iolock. * on the iolock.
*/ */
xfs_wait_for_freeze(mp, SB_FREEZE_TRANS); tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS, true);
tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
tp->t_flags |= XFS_TRANS_RESERVE; tp->t_flags |= XFS_TRANS_RESERVE;
error = xfs_trans_reserve(tp, resblks, error = xfs_trans_reserve(tp, resblks,
XFS_WRITE_LOG_RES(mp), 0, XFS_WRITE_LOG_RES(mp), 0,
......
...@@ -1566,15 +1566,9 @@ xfs_fs_writable(xfs_mount_t *mp) ...@@ -1566,15 +1566,9 @@ xfs_fs_writable(xfs_mount_t *mp)
} }
/* /*
* xfs_log_sbcount
*
* Called either periodically to keep the on disk superblock values * Called either periodically to keep the on disk superblock values
* roughly up to date or from unmount to make sure the values are * roughly up to date or from unmount to make sure the values are
* correct on a clean unmount. * 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 int
xfs_log_sbcount( xfs_log_sbcount(
...@@ -1596,7 +1590,13 @@ xfs_log_sbcount( ...@@ -1596,7 +1590,13 @@ xfs_log_sbcount(
if (!xfs_sb_version_haslazysbcount(&mp->m_sb)) if (!xfs_sb_version_haslazysbcount(&mp->m_sb))
return 0; 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, error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
XFS_DEFAULT_LOG_COUNT); XFS_DEFAULT_LOG_COUNT);
if (error) { if (error) {
......
...@@ -566,31 +566,24 @@ xfs_trans_init( ...@@ -566,31 +566,24 @@ xfs_trans_init(
/* /*
* This routine is called to allocate a transaction structure. * This routine is called to allocate a transaction structure.
*
* The type parameter indicates the type of the transaction. These * The type parameter indicates the type of the transaction. These
* are enumerated in xfs_trans.h. * 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 * struct xfs_trans *
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( _xfs_trans_alloc(
xfs_mount_t *mp, struct xfs_mount *mp,
uint type, uint type,
uint memflags) uint memflags,
bool wait_for_freeze)
{ {
xfs_trans_t *tp; struct xfs_trans *tp;
atomic_inc(&mp->m_active_trans); 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 = kmem_zone_zalloc(xfs_trans_zone, memflags);
tp->t_magic = XFS_TRANS_MAGIC; tp->t_magic = XFS_TRANS_MAGIC;
tp->t_type = type; tp->t_type = type;
......
...@@ -447,8 +447,14 @@ typedef struct xfs_trans { ...@@ -447,8 +447,14 @@ typedef struct xfs_trans {
/* /*
* XFS transaction mechanism exported interfaces. * 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, bool);
xfs_trans_t *_xfs_trans_alloc(struct xfs_mount *, uint, uint);
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 *); xfs_trans_t *xfs_trans_dup(xfs_trans_t *);
int xfs_trans_reserve(xfs_trans_t *, uint, uint, uint, int xfs_trans_reserve(xfs_trans_t *, uint, uint, uint,
uint, uint); uint, uint);
......
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