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xfs: xfs_iflush() is no longer necessary

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Now we have a cached buffer on inode log items, we don't need
to do buffer lookups when flushing inodes anymore - all we need
to do is lock the buffer and we are ready to go.

This largely gets rid of the need for xfs_iflush(), which is
essentially just a mechanism to look up the buffer and flush the
inode to it. Instead, we can just call xfs_iflush_cluster() with a
few modifications to ensure it also flushes the inode we already
hold locked.

This allows the AIL inode item pushing to be almost entirely
non-blocking in XFS - we won't block unless memory allocation
for the cluster inode lookup blocks or the block device queues are
full.

Writeback during inode reclaim becomes a little more complex because
we now have to lock the buffer ourselves, but otherwise this change
is largely a functional no-op that removes a whole lot of code.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Dave Chinner 2020-06-29 14:49:19 -07:00 committed by Darrick J. Wong
parent 48d55e2ae3
commit 90c60e1640
3 changed files with 34 additions and 128 deletions
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107
fs/xfs/xfs_inode.c
View File

@ -3450,7 +3450,18 @@ out_release_wip:
return error;
}
STATIC int
/*
* Non-blocking flush of dirty inode metadata into the backing buffer.
*
* The caller must have a reference to the inode and hold the cluster buffer
* locked. The function will walk across all the inodes on the cluster buffer it
* can find and lock without blocking, and flush them to the cluster buffer.
*
* On success, the caller must write out the buffer returned in *bp and
* release it. On failure, the filesystem will be shut down, the buffer will
* have been unlocked and released, and EFSCORRUPTED will be returned.
*/
int
xfs_iflush_cluster(
struct xfs_inode *ip,
struct xfs_buf *bp)
@ -3485,8 +3496,6 @@ xfs_iflush_cluster(
for (i = 0; i < nr_found; i++) {
cip = cilist[i];
if (cip == ip)
continue;
/*
* because this is an RCU protected lookup, we could find a
@ -3577,99 +3586,11 @@ out_free:
kmem_free(cilist);
out_put:
xfs_perag_put(pag);
return error;
}
/*
* Flush dirty inode metadata into the backing buffer.
*
* The caller must have the inode lock and the inode flush lock held. The
* inode lock will still be held upon return to the caller, and the inode
* flush lock will be released after the inode has reached the disk.
*
* The caller must write out the buffer returned in *bpp and release it.
*/
int
xfs_iflush(
struct xfs_inode *ip,
struct xfs_buf **bpp)
{
struct xfs_mount *mp = ip->i_mount;
struct xfs_buf *bp = NULL;
struct xfs_dinode *dip;
int error;
XFS_STATS_INC(mp, xs_iflush_count);
ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
ASSERT(xfs_isiflocked(ip));
ASSERT(ip->i_df.if_format != XFS_DINODE_FMT_BTREE ||
ip->i_df.if_nextents > XFS_IFORK_MAXEXT(ip, XFS_DATA_FORK));
*bpp = NULL;
xfs_iunpin_wait(ip);
/*
* For stale inodes we cannot rely on the backing buffer remaining
* stale in cache for the remaining life of the stale inode and so
* xfs_imap_to_bp() below may give us a buffer that no longer contains
* inodes below. We have to check this after ensuring the inode is
* unpinned so that it is safe to reclaim the stale inode after the
* flush call.
*/
if (xfs_iflags_test(ip, XFS_ISTALE)) {
xfs_ifunlock(ip);
return 0;
}
/*
* Get the buffer containing the on-disk inode. We are doing a try-lock
* operation here, so we may get an EAGAIN error. In that case, return
* leaving the inode dirty.
*
* If we get any other error, we effectively have a corruption situation
* and we cannot flush the inode. Abort the flush and shut down.
*/
error = xfs_imap_to_bp(mp, NULL, &ip->i_imap, &dip, &bp, XBF_TRYLOCK);
if (error == -EAGAIN) {
xfs_ifunlock(ip);
return error;
}
if (error)
goto abort;
/*
* If the buffer is pinned then push on the log now so we won't
* get stuck waiting in the write for too long.
*/
if (xfs_buf_ispinned(bp))
xfs_log_force(mp, 0);
/*
* Flush the provided inode then attempt to gather others from the
* cluster into the write.
*
* Note: Once we attempt to flush an inode, we must run buffer
* completion callbacks on any failure. If this fails, simulate an I/O
* failure on the buffer and shut down.
*/
error = xfs_iflush_int(ip, bp);
if (!error)
error = xfs_iflush_cluster(ip, bp);
if (error) {
bp->b_flags |= XBF_ASYNC;
xfs_buf_ioend_fail(bp);
goto shutdown;
xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
}
*bpp = bp;
return 0;
abort:
xfs_iflush_abort(ip);
shutdown:
xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
return error;
}
@ -3687,7 +3608,7 @@ xfs_iflush_int(
ASSERT(xfs_isiflocked(ip));
ASSERT(ip->i_df.if_format != XFS_DINODE_FMT_BTREE ||
ip->i_df.if_nextents > XFS_IFORK_MAXEXT(ip, XFS_DATA_FORK));
ASSERT(iip != NULL && iip->ili_fields != 0);
ASSERT(iip->ili_item.li_buf == bp);
dip = xfs_buf_offset(bp, ip->i_imap.im_boffset);

2
fs/xfs/xfs_inode.h
View File

@ -426,7 +426,7 @@ int xfs_log_force_inode(struct xfs_inode *ip);
void xfs_iunpin_wait(xfs_inode_t *);
#define xfs_ipincount(ip) ((unsigned int) atomic_read(&ip->i_pincount))
int xfs_iflush(struct xfs_inode *, struct xfs_buf **);
int xfs_iflush_cluster(struct xfs_inode *, struct xfs_buf *);
void xfs_lock_two_inodes(struct xfs_inode *ip0, uint ip0_mode,
struct xfs_inode *ip1, uint ip1_mode);

53
fs/xfs/xfs_inode_item.c
View File

@ -485,53 +485,38 @@ xfs_inode_item_push(
uint rval = XFS_ITEM_SUCCESS;
int error;
if (xfs_ipincount(ip) > 0)
ASSERT(iip->ili_item.li_buf);
if (xfs_ipincount(ip) > 0 || xfs_buf_ispinned(bp) ||
(ip->i_flags & XFS_ISTALE))
return XFS_ITEM_PINNED;
if (!xfs_ilock_nowait(ip, XFS_ILOCK_SHARED))
/* If the inode is already flush locked, we're already flushing. */
if (xfs_isiflocked(ip))
return XFS_ITEM_FLUSHING;
if (!xfs_buf_trylock(bp))
return XFS_ITEM_LOCKED;
/*
* Re-check the pincount now that we stabilized the value by
* taking the ilock.
*/
if (xfs_ipincount(ip) > 0) {
rval = XFS_ITEM_PINNED;
goto out_unlock;
}
/*
* Stale inode items should force out the iclog.
*/
if (ip->i_flags & XFS_ISTALE) {
rval = XFS_ITEM_PINNED;
goto out_unlock;
}
/*
* Someone else is already flushing the inode. Nothing we can do
* here but wait for the flush to finish and remove the item from
* the AIL.
*/
if (!xfs_iflock_nowait(ip)) {
rval = XFS_ITEM_FLUSHING;
goto out_unlock;
}
ASSERT(iip->ili_fields != 0 || XFS_FORCED_SHUTDOWN(ip->i_mount));
spin_unlock(&lip->li_ailp->ail_lock);
error = xfs_iflush(ip, &bp);
/*
* We need to hold a reference for flushing the cluster buffer as it may
* fail the buffer without IO submission. In which case, we better get a
* reference for that completion because otherwise we don't get a
* reference for IO until we queue the buffer for delwri submission.
*/
xfs_buf_hold(bp);
error = xfs_iflush_cluster(ip, bp);
if (!error) {
if (!xfs_buf_delwri_queue(bp, buffer_list))
rval = XFS_ITEM_FLUSHING;
xfs_buf_relse(bp);
} else if (error == -EAGAIN)
} else {
rval = XFS_ITEM_LOCKED;
}
spin_lock(&lip->li_ailp->ail_lock);
out_unlock:
xfs_iunlock(ip, XFS_ILOCK_SHARED);
return rval;
}