From 3070451eea1ed8e3bde0573183c7d8ac25fd5e97 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Thu, 24 Jun 2010 11:42:19 +1000 Subject: [PATCH] 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 Reviewed-by: Dave Chinner --- fs/xfs/xfs_iomap.c | 52 +++++++++++++++++++++++++--------------------- 1 file changed, 28 insertions(+), 24 deletions(-) diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index 39ad46b3ed4..a0dbcaff911 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -242,7 +242,7 @@ xfs_iomap_write_direct( 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 @@ xfs_iomap_write_direct( 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 @@ xfs_iomap_write_direct( 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 @@ xfs_iomap_write_direct( 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 @@ xfs_iomap_write_direct( 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_iomap_write_allocate( 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_iomap_write_allocate( 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 @@ xfs_iomap_write_allocate( 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 @@ xfs_iomap_write_allocate( } } - /* 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 @@ xfs_iomap_write_allocate( * 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 @@ xfs_iomap_write_allocate( * 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: -- 2.43.2