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xfs: xfs_iflock is no longer a completion

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With the recent rework of the inode cluster flushing, we no longer
ever wait on the the inode flush "lock". It was never a lock in the
first place, just a completion to allow callers to wait for inode IO
to complete. We now never wait for flush completion as all inode
flushing is non-blocking. Hence we can get rid of all the iflock
infrastructure and instead just set and check a state flag.

Rename the XFS_IFLOCK flag to XFS_IFLUSHING, convert all the
xfs_iflock_nowait() test-and-set operations on that flag, and
replace all the xfs_ifunlock() calls to clear operations.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Dave Chinner 2020-08-17 16:41:01 -07:00 committed by Darrick J. Wong
parent 771915c4f6
commit 718ecc5035
7 changed files with 55 additions and 108 deletions
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17
fs/xfs/xfs_icache.c
View File

@ -52,7 +52,6 @@ xfs_inode_alloc(
XFS_STATS_INC(mp, vn_active);
ASSERT(atomic_read(&ip->i_pincount) == 0);
ASSERT(!xfs_isiflocked(ip));
ASSERT(ip->i_ino == 0);
/* initialise the xfs inode */
@ -123,7 +122,7 @@ void
xfs_inode_free(
struct xfs_inode *ip)
{
ASSERT(!xfs_isiflocked(ip));
ASSERT(!xfs_iflags_test(ip, XFS_IFLUSHING));
/*
* Because we use RCU freeing we need to ensure the inode always
@ -1035,23 +1034,21 @@ xfs_reclaim_inode(
if (!xfs_ilock_nowait(ip, XFS_ILOCK_EXCL))
goto out;
if (!xfs_iflock_nowait(ip))
if (xfs_iflags_test_and_set(ip, XFS_IFLUSHING))
goto out_iunlock;
if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
xfs_iunpin_wait(ip);
/* xfs_iflush_abort() drops the flush lock */
xfs_iflush_abort(ip);
goto reclaim;
}
if (xfs_ipincount(ip))
goto out_ifunlock;
goto out_clear_flush;
if (!xfs_inode_clean(ip))
goto out_ifunlock;
goto out_clear_flush;
xfs_ifunlock(ip);
xfs_iflags_clear(ip, XFS_IFLUSHING);
reclaim:
ASSERT(!xfs_isiflocked(ip));
/*
* Because we use RCU freeing we need to ensure the inode always appears
@ -1101,8 +1098,8 @@ reclaim:
__xfs_inode_free(ip);
return;
out_ifunlock:
xfs_ifunlock(ip);
out_clear_flush:
xfs_iflags_clear(ip, XFS_IFLUSHING);
out_iunlock:
xfs_iunlock(ip, XFS_ILOCK_EXCL);
out:

73
fs/xfs/xfs_inode.c
View File

@ -598,22 +598,6 @@ xfs_lock_two_inodes(
}
}
void
__xfs_iflock(
struct xfs_inode *ip)
{
wait_queue_head_t *wq = bit_waitqueue(&ip->i_flags, __XFS_IFLOCK_BIT);
DEFINE_WAIT_BIT(wait, &ip->i_flags, __XFS_IFLOCK_BIT);
do {
prepare_to_wait_exclusive(wq, &wait.wq_entry, TASK_UNINTERRUPTIBLE);
if (xfs_isiflocked(ip))
io_schedule();
} while (!xfs_iflock_nowait(ip));
finish_wait(wq, &wait.wq_entry);
}
STATIC uint
_xfs_dic2xflags(
uint16_t di_flags,
@ -2531,11 +2515,8 @@ retry:
* valid, the wrong inode or stale.
*/
spin_lock(&ip->i_flags_lock);
if (ip->i_ino != inum || __xfs_iflags_test(ip, XFS_ISTALE)) {
spin_unlock(&ip->i_flags_lock);
rcu_read_unlock();
return;
}
if (ip->i_ino != inum || __xfs_iflags_test(ip, XFS_ISTALE))
goto out_iflags_unlock;
/*
* Don't try to lock/unlock the current inode, but we _cannot_ skip the
@ -2552,16 +2533,14 @@ retry:
}
}
ip->i_flags |= XFS_ISTALE;
spin_unlock(&ip->i_flags_lock);
rcu_read_unlock();
/*
* If we can't get the flush lock, the inode is already attached. All
* If the inode is flushing, it is already attached to the buffer. All
* we needed to do here is mark the inode stale so buffer IO completion
* will remove it from the AIL.
*/
iip = ip->i_itemp;
if (!xfs_iflock_nowait(ip)) {
if (__xfs_iflags_test(ip, XFS_IFLUSHING)) {
ASSERT(!list_empty(&iip->ili_item.li_bio_list));
ASSERT(iip->ili_last_fields);
goto out_iunlock;
@ -2573,10 +2552,12 @@ retry:
* commit as the flock synchronises removal of the inode from the
* cluster buffer against inode reclaim.
*/
if (!iip || list_empty(&iip->ili_item.li_bio_list)) {
xfs_ifunlock(ip);
if (!iip || list_empty(&iip->ili_item.li_bio_list))
goto out_iunlock;
}
__xfs_iflags_set(ip, XFS_IFLUSHING);
spin_unlock(&ip->i_flags_lock);
rcu_read_unlock();
/* we have a dirty inode in memory that has not yet been flushed. */
spin_lock(&iip->ili_lock);
@ -2586,9 +2567,16 @@ retry:
spin_unlock(&iip->ili_lock);
ASSERT(iip->ili_last_fields);
if (ip != free_ip)
xfs_iunlock(ip, XFS_ILOCK_EXCL);
return;
out_iunlock:
if (ip != free_ip)
xfs_iunlock(ip, XFS_ILOCK_EXCL);
out_iflags_unlock:
spin_unlock(&ip->i_flags_lock);
rcu_read_unlock();
}
/*
@ -2631,8 +2619,9 @@ xfs_ifree_cluster(
/*
* We obtain and lock the backing buffer first in the process
* here, as we have to ensure that any dirty inode that we
* can't get the flush lock on is attached to the buffer.
* here to ensure dirty inodes attached to the buffer remain in
* the flushing state while we mark them stale.
*
* If we scan the in-memory inodes first, then buffer IO can
* complete before we get a lock on it, and hence we may fail
* to mark all the active inodes on the buffer stale.
@ -3443,7 +3432,7 @@ xfs_iflush(
int error;
ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
ASSERT(xfs_isiflocked(ip));
ASSERT(xfs_iflags_test(ip, XFS_IFLUSHING));
ASSERT(ip->i_df.if_format != XFS_DINODE_FMT_BTREE ||
ip->i_df.if_nextents > XFS_IFORK_MAXEXT(ip, XFS_DATA_FORK));
ASSERT(iip->ili_item.li_buf == bp);
@ -3613,7 +3602,7 @@ xfs_iflush_cluster(
/*
* Quick and dirty check to avoid locks if possible.
*/
if (__xfs_iflags_test(ip, XFS_IRECLAIM | XFS_IFLOCK))
if (__xfs_iflags_test(ip, XFS_IRECLAIM | XFS_IFLUSHING))
continue;
if (xfs_ipincount(ip))
continue;
@ -3627,7 +3616,7 @@ xfs_iflush_cluster(
*/
spin_lock(&ip->i_flags_lock);
ASSERT(!__xfs_iflags_test(ip, XFS_ISTALE));
if (__xfs_iflags_test(ip, XFS_IRECLAIM | XFS_IFLOCK)) {
if (__xfs_iflags_test(ip, XFS_IRECLAIM | XFS_IFLUSHING)) {
spin_unlock(&ip->i_flags_lock);
continue;
}
@ -3635,23 +3624,16 @@ xfs_iflush_cluster(
/*
* ILOCK will pin the inode against reclaim and prevent
* concurrent transactions modifying the inode while we are
* flushing the inode.
* flushing the inode. If we get the lock, set the flushing
* state before we drop the i_flags_lock.
*/
if (!xfs_ilock_nowait(ip, XFS_ILOCK_SHARED)) {
spin_unlock(&ip->i_flags_lock);
continue;
}
__xfs_iflags_set(ip, XFS_IFLUSHING);
spin_unlock(&ip->i_flags_lock);
/*
* Skip inodes that are already flush locked as they have
* already been written to the buffer.
*/
if (!xfs_iflock_nowait(ip)) {
xfs_iunlock(ip, XFS_ILOCK_SHARED);
continue;
}
/*
* Abort flushing this inode if we are shut down because the
* inode may not currently be in the AIL. This can occur when
@ -3661,7 +3643,6 @@ xfs_iflush_cluster(
*/
if (XFS_FORCED_SHUTDOWN(mp)) {
xfs_iunpin_wait(ip);
/* xfs_iflush_abort() drops the flush lock */
xfs_iflush_abort(ip);
xfs_iunlock(ip, XFS_ILOCK_SHARED);
error = -EIO;
@ -3670,7 +3651,7 @@ xfs_iflush_cluster(
/* don't block waiting on a log force to unpin dirty inodes */
if (xfs_ipincount(ip)) {
xfs_ifunlock(ip);
xfs_iflags_clear(ip, XFS_IFLUSHING);
xfs_iunlock(ip, XFS_ILOCK_SHARED);
continue;
}
@ -3678,7 +3659,7 @@ xfs_iflush_cluster(
if (!xfs_inode_clean(ip))
error = xfs_iflush(ip, bp);
else
xfs_ifunlock(ip);
xfs_iflags_clear(ip, XFS_IFLUSHING);
xfs_iunlock(ip, XFS_ILOCK_SHARED);
if (error)
break;

33
fs/xfs/xfs_inode.h
View File

@ -211,8 +211,7 @@ static inline bool xfs_inode_has_cow_data(struct xfs_inode *ip)
#define XFS_INEW (1 << __XFS_INEW_BIT)
#define XFS_ITRUNCATED (1 << 5) /* truncated down so flush-on-close */
#define XFS_IDIRTY_RELEASE (1 << 6) /* dirty release already seen */
#define __XFS_IFLOCK_BIT 7 /* inode is being flushed right now */
#define XFS_IFLOCK (1 << __XFS_IFLOCK_BIT)
#define XFS_IFLUSHING (1 << 7) /* inode is being flushed */
#define __XFS_IPINNED_BIT 8 /* wakeup key for zero pin count */
#define XFS_IPINNED (1 << __XFS_IPINNED_BIT)
#define XFS_IEOFBLOCKS (1 << 9) /* has the preallocblocks tag set */
@ -233,36 +232,6 @@ static inline bool xfs_inode_has_cow_data(struct xfs_inode *ip)
(XFS_IRECLAIMABLE | XFS_IRECLAIM | \
XFS_IDIRTY_RELEASE | XFS_ITRUNCATED)
/*
* Synchronize processes attempting to flush the in-core inode back to disk.
*/
static inline int xfs_isiflocked(struct xfs_inode *ip)
{
return xfs_iflags_test(ip, XFS_IFLOCK);
}
extern void __xfs_iflock(struct xfs_inode *ip);
static inline int xfs_iflock_nowait(struct xfs_inode *ip)
{
return !xfs_iflags_test_and_set(ip, XFS_IFLOCK);
}
static inline void xfs_iflock(struct xfs_inode *ip)
{
if (!xfs_iflock_nowait(ip))
__xfs_iflock(ip);
}
static inline void xfs_ifunlock(struct xfs_inode *ip)
{
ASSERT(xfs_isiflocked(ip));
xfs_iflags_clear(ip, XFS_IFLOCK);
smp_mb();
wake_up_bit(&ip->i_flags, __XFS_IFLOCK_BIT);
}
/*
* Flags for inode locking.
* Bit ranges: 1<<1 - 1<<16-1 -- iolock/ilock modes (bitfield)

15
fs/xfs/xfs_inode_item.c
View File

@ -491,8 +491,7 @@ xfs_inode_item_push(
(ip->i_flags & XFS_ISTALE))
return XFS_ITEM_PINNED;
/* If the inode is already flush locked, we're already flushing. */
if (xfs_isiflocked(ip))
if (xfs_iflags_test(ip, XFS_IFLUSHING))
return XFS_ITEM_FLUSHING;
if (!xfs_buf_trylock(bp))
@ -703,7 +702,7 @@ xfs_iflush_finish(
iip->ili_last_fields = 0;
iip->ili_flush_lsn = 0;
spin_unlock(&iip->ili_lock);
xfs_ifunlock(iip->ili_inode);
xfs_iflags_clear(iip->ili_inode, XFS_IFLUSHING);
if (drop_buffer)
xfs_buf_rele(bp);
}
@ -711,8 +710,8 @@ xfs_iflush_finish(
/*
* Inode buffer IO completion routine. It is responsible for removing inodes
* attached to the buffer from the AIL if they have not been re-logged, as well
* as completing the flush and unlocking the inode.
* attached to the buffer from the AIL if they have not been re-logged and
* completing the inode flush.
*/
void
xfs_iflush_done(
@ -755,10 +754,10 @@ xfs_iflush_done(
}
/*
* This is the inode flushing abort routine. It is called from xfs_iflush when
* This is the inode flushing abort routine. It is called when
* the filesystem is shutting down to clean up the inode state. It is
* responsible for removing the inode item from the AIL if it has not been
* re-logged, and unlocking the inode's flush lock.
* re-logged and clearing the inode's flush state.
*/
void
xfs_iflush_abort(
@ -790,7 +789,7 @@ xfs_iflush_abort(
list_del_init(&iip->ili_item.li_bio_list);
spin_unlock(&iip->ili_lock);
}
xfs_ifunlock(ip);
xfs_iflags_clear(ip, XFS_IFLUSHING);
if (bp)
xfs_buf_rele(bp);
}

4
fs/xfs/xfs_inode_item.h
View File

@ -25,8 +25,8 @@ struct xfs_inode_log_item {
*
* We need atomic changes between inode dirtying, inode flushing and
* inode completion, but these all hold different combinations of
* ILOCK and iflock and hence we need some other method of serialising
* updates to the flush state.
* ILOCK and IFLUSHING and hence we need some other method of
* serialising updates to the flush state.
*/
spinlock_t ili_lock; /* flush state lock */
unsigned int ili_last_fields; /* fields when flushed */

11
fs/xfs/xfs_mount.c
View File

@ -1059,11 +1059,12 @@ xfs_unmountfs(
* We can potentially deadlock here if we have an inode cluster
* that has been freed has its buffer still pinned in memory because
* the transaction is still sitting in a iclog. The stale inodes
* on that buffer will have their flush locks held until the
* transaction hits the disk and the callbacks run. the inode
* flush takes the flush lock unconditionally and with nothing to
* push out the iclog we will never get that unlocked. hence we
* need to force the log first.
* on that buffer will be pinned to the buffer until the
* transaction hits the disk and the callbacks run. Pushing the AIL will
* skip the stale inodes and may never see the pinned buffer, so
* nothing will push out the iclog and unpin the buffer. Hence we
* need to force the log here to ensure all items are flushed into the
* AIL before we go any further.
*/
xfs_log_force(mp, XFS_LOG_SYNC);

10
fs/xfs/xfs_super.c
View File

@ -654,11 +654,11 @@ xfs_fs_destroy_inode(
ASSERT_ALWAYS(!xfs_iflags_test(ip, XFS_IRECLAIM));
/*
* We always use background reclaim here because even if the
* inode is clean, it still may be under IO and hence we have
* to take the flush lock. The background reclaim path handles
* this more efficiently than we can here, so simply let background
* reclaim tear down all inodes.
* We always use background reclaim here because even if the inode is
* clean, it still may be under IO and hence we have wait for IO
* completion to occur before we can reclaim the inode. The background
* reclaim path handles this more efficiently than we can here, so
* simply let background reclaim tear down all inodes.
*/
xfs_inode_set_reclaim_tag(ip);
}