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xfs: remove unnecessary dirty bli format check for ordered bufs 

xfs_buf_item_unlock() historically checked the dirty state of the
buffer by manually checking the buffer log formats for dirty
segments. The introduction of ordered buffers invalidated this check
because ordered buffers have dirty bli's but no dirty (logged)
segments. The check was updated to accommodate ordered buffers by
looking at the bli state first and considering the blf only if the
bli is clean.

This logic is safe but unnecessary. There is no valid case where the
bli is clean yet the blf has dirty segments. The bli is set dirty
whenever the blf is logged (via xfs_trans_log_buf()) and the blf is
cleared in the only place BLI_DIRTY is cleared (xfs_trans_binval()).

Remove the conditional blf dirty checks and replace with an assert
that should catch any discrepencies between bli and blf dirty
states. Refactor the old blf dirty check into a helper function to
be used by the assert.

Signed-off-by: Brian Foster <bfoster@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:
Brian Foster 2017-08-29 10:08:37 -07:00 committed by Darrick J. Wong
parent a4f6cf6b2b
commit 6453c65d35
2 changed files with 33 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

62
fs/xfs/xfs_buf_item.c
View File

@ -575,26 +575,18 @@ xfs_buf_item_unlock(
{
struct xfs_buf_log_item *bip = BUF_ITEM(lip);
struct xfs_buf *bp = bip->bli_buf;
bool clean;
bool aborted;
int flags;
bool aborted = !!(lip->li_flags & XFS_LI_ABORTED);
bool hold = !!(bip->bli_flags & XFS_BLI_HOLD);
bool dirty = !!(bip->bli_flags & XFS_BLI_DIRTY);
bool ordered = !!(bip->bli_flags & XFS_BLI_ORDERED);
/* Clear the buffer's association with this transaction. */
bp->b_transp = NULL;
/*
* If this is a transaction abort, don't return early. Instead, allow
* the brelse to happen. Normally it would be done for stale
* (cancelled) buffers at unpin time, but we'll never go through the
* pin/unpin cycle if we abort inside commit.
* The per-transaction state has been copied above so clear it from the
* bli.
*/
aborted = (lip->li_flags & XFS_LI_ABORTED) ? true : false;
/*
* Before possibly freeing the buf item, copy the per-transaction state
* so we can reference it safely later after clearing it from the
* buffer log item.
*/
flags = bip->bli_flags;
bip->bli_flags &= ~(XFS_BLI_LOGGED | XFS_BLI_HOLD | XFS_BLI_ORDERED);
/*
@ -602,7 +594,7 @@ xfs_buf_item_unlock(
* unlock the buffer and free the buf item when the buffer is unpinned
* for the last time.
*/
if (flags & XFS_BLI_STALE) {
if (bip->bli_flags & XFS_BLI_STALE) {
trace_xfs_buf_item_unlock_stale(bip);
ASSERT(bip->__bli_format.blf_flags & XFS_BLF_CANCEL);
if (!aborted) {
@ -620,20 +612,11 @@ xfs_buf_item_unlock(
* regardless of whether it is dirty or not. A dirty abort implies a
* shutdown, anyway.
*
* Ordered buffers are dirty but may have no recorded changes, so ensure
* we only release clean items here.
* The bli dirty state should match whether the blf has logged segments
* except for ordered buffers, where only the bli should be dirty.
*/
clean = (flags & XFS_BLI_DIRTY) ? false : true;
if (clean) {
int i;
for (i = 0; i < bip->bli_format_count; i++) {
if (!xfs_bitmap_empty(bip->bli_formats[i].blf_data_map,
bip->bli_formats[i].blf_map_size)) {
clean = false;
break;
}
}
}
ASSERT((!ordered && dirty == xfs_buf_item_dirty_format(bip)) ||
(ordered && dirty && !xfs_buf_item_dirty_format(bip)));
/*
* Clean buffers, by definition, cannot be in the AIL. However, aborted
@ -652,11 +635,11 @@ xfs_buf_item_unlock(
ASSERT(XFS_FORCED_SHUTDOWN(lip->li_mountp));
xfs_trans_ail_remove(lip, SHUTDOWN_LOG_IO_ERROR);
xfs_buf_item_relse(bp);
} else if (clean)
} else if (!dirty)
xfs_buf_item_relse(bp);
}
if (!(flags & XFS_BLI_HOLD))
if (!hold)
xfs_buf_relse(bp);
}
@ -945,6 +928,25 @@ xfs_buf_item_log(
}
/*
* Return true if the buffer has any ranges logged/dirtied by a transaction,
* false otherwise.
*/
bool
xfs_buf_item_dirty_format(
struct xfs_buf_log_item *bip)
{
int i;
for (i = 0; i < bip->bli_format_count; i++) {
if (!xfs_bitmap_empty(bip->bli_formats[i].blf_data_map,
bip->bli_formats[i].blf_map_size))
return true;
}
return false;
}
STATIC void
xfs_buf_item_free(
xfs_buf_log_item_t *bip)

1
fs/xfs/xfs_buf_item.h
View File

@ -64,6 +64,7 @@ typedef struct xfs_buf_log_item {
int xfs_buf_item_init(struct xfs_buf *, struct xfs_mount *);
void xfs_buf_item_relse(struct xfs_buf *);
void xfs_buf_item_log(xfs_buf_log_item_t *, uint, uint);
bool xfs_buf_item_dirty_format(struct xfs_buf_log_item *);
void xfs_buf_attach_iodone(struct xfs_buf *,
void(*)(struct xfs_buf *, xfs_log_item_t *),
xfs_log_item_t *);