xfs: reduce stack usage in xfs_iomap
xfs_iomap passes a xfs_bmbt_irec pointer to xfs_iomap_write_direct and
xfs_iomap_write_allocate to give them the results of our read-only
xfs_bmapi query. Instead of allocating a new xfs_bmbt_irec on stack
for the next call to xfs_bmapi re use the one we got passed as it's not
used after this point.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 39ad46b..a0dbcaf 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -242,7 +242,7 @@
xfs_off_t offset,
size_t count,
int flags,
- xfs_bmbt_irec_t *ret_imap,
+ xfs_bmbt_irec_t *imap,
int *nmaps)
{
xfs_mount_t *mp = ip->i_mount;
@@ -256,7 +256,6 @@
int quota_flag;
int rt;
xfs_trans_t *tp;
- xfs_bmbt_irec_t imap;
xfs_bmap_free_t free_list;
uint qblocks, resblks, resrtextents;
int committed;
@@ -280,10 +279,10 @@
if (error)
goto error_out;
} else {
- if (*nmaps && (ret_imap->br_startblock == HOLESTARTBLOCK))
+ if (*nmaps && (imap->br_startblock == HOLESTARTBLOCK))
last_fsb = MIN(last_fsb, (xfs_fileoff_t)
- ret_imap->br_blockcount +
- ret_imap->br_startoff);
+ imap->br_blockcount +
+ imap->br_startoff);
}
count_fsb = last_fsb - offset_fsb;
ASSERT(count_fsb > 0);
@@ -336,12 +335,15 @@
bmapi_flag |= XFS_BMAPI_PREALLOC;
/*
- * Issue the xfs_bmapi() call to allocate the blocks
+ * Issue the xfs_bmapi() call to allocate the blocks.
+ *
+ * From this point onwards we overwrite the imap pointer that the
+ * caller gave to us.
*/
xfs_bmap_init(&free_list, &firstfsb);
nimaps = 1;
error = xfs_bmapi(tp, ip, offset_fsb, count_fsb, bmapi_flag,
- &firstfsb, 0, &imap, &nimaps, &free_list);
+ &firstfsb, 0, imap, &nimaps, &free_list);
if (error)
goto error0;
@@ -363,12 +365,11 @@
goto error_out;
}
- if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip))) {
- error = xfs_cmn_err_fsblock_zero(ip, &imap);
+ if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip))) {
+ error = xfs_cmn_err_fsblock_zero(ip, imap);
goto error_out;
}
- *ret_imap = imap;
*nmaps = 1;
return 0;
@@ -542,7 +543,7 @@
xfs_inode_t *ip,
xfs_off_t offset,
size_t count,
- xfs_bmbt_irec_t *map,
+ xfs_bmbt_irec_t *imap,
int *retmap)
{
xfs_mount_t *mp = ip->i_mount;
@@ -551,7 +552,6 @@
xfs_fsblock_t first_block;
xfs_bmap_free_t free_list;
xfs_filblks_t count_fsb;
- xfs_bmbt_irec_t imap;
xfs_trans_t *tp;
int nimaps, committed;
int error = 0;
@@ -567,8 +567,8 @@
return XFS_ERROR(error);
offset_fsb = XFS_B_TO_FSBT(mp, offset);
- count_fsb = map->br_blockcount;
- map_start_fsb = map->br_startoff;
+ count_fsb = imap->br_blockcount;
+ map_start_fsb = imap->br_startoff;
XFS_STATS_ADD(xs_xstrat_bytes, XFS_FSB_TO_B(mp, count_fsb));
@@ -647,10 +647,15 @@
}
}
- /* Go get the actual blocks */
+ /*
+ * Go get the actual blocks.
+ *
+ * From this point onwards we overwrite the imap
+ * pointer that the caller gave to us.
+ */
error = xfs_bmapi(tp, ip, map_start_fsb, count_fsb,
XFS_BMAPI_WRITE, &first_block, 1,
- &imap, &nimaps, &free_list);
+ imap, &nimaps, &free_list);
if (error)
goto trans_cancel;
@@ -669,13 +674,12 @@
* See if we were able to allocate an extent that
* covers at least part of the callers request
*/
- if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip)))
- return xfs_cmn_err_fsblock_zero(ip, &imap);
+ if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))
+ return xfs_cmn_err_fsblock_zero(ip, imap);
- if ((offset_fsb >= imap.br_startoff) &&
- (offset_fsb < (imap.br_startoff +
- imap.br_blockcount))) {
- *map = imap;
+ if ((offset_fsb >= imap->br_startoff) &&
+ (offset_fsb < (imap->br_startoff +
+ imap->br_blockcount))) {
*retmap = 1;
XFS_STATS_INC(xs_xstrat_quick);
return 0;
@@ -685,8 +689,8 @@
* So far we have not mapped the requested part of the
* file, just surrounding data, try again.
*/
- count_fsb -= imap.br_blockcount;
- map_start_fsb = imap.br_startoff + imap.br_blockcount;
+ count_fsb -= imap->br_blockcount;
+ map_start_fsb = imap->br_startoff + imap->br_blockcount;
}
trans_cancel:
