xfs: cleanup picking the start extent hint in xfs_bmap_rtalloc

Clean up the logical in xfs_bmap_rtalloc that tries to find a rtextent
to start the search from by using a separate variable for the hint, not
calling xfs_bmap_adjacent when we want to ignore the locality and avoid
an extra roundtrip converting between block numbers and RT extent
numbers.

As a side-effect this doesn't pointlessly call xfs_rtpick_extent and
increment the start rtextent hint if we are going to ignore the result
anyway.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
index 92ff05ce33c71387113f44bcf80af742a1bc0e78..33f55816664258ddcc9184ecc1833e318c7a8a87 100644 (file)
--- a/fs/xfs/xfs_rtalloc.c
+++ b/fs/xfs/xfs_rtalloc.c
@@ -1398,7 +1398,8 @@ xfs_bmap_rtalloc(
 {
        struct xfs_mount        *mp = ap->ip->i_mount;
        xfs_fileoff_t           orig_offset = ap->offset;
-       xfs_rtxnum_t            rtx;
+       xfs_rtxnum_t            start;     /* allocation hint rtextent no */
+       xfs_rtxnum_t            rtx;       /* actually allocated rtextent no */
        xfs_rtxlen_t            prod = 0;  /* product factor for allocators */
        xfs_extlen_t            mod = 0;   /* product factor for allocators */
        xfs_rtxlen_t            ralen = 0; /* realtime allocation length */
@@ -1459,30 +1460,24 @@ xfs_bmap_rtalloc(
                rtlocked = true;
        }
 
-       /*
-        * If it's an allocation to an empty file at offset 0,
-        * pick an extent that will space things out in the rt area.
-        */
-       if (ap->eof && ap->offset == 0) {
-               error = xfs_rtpick_extent(mp, ap->tp, ralen, &rtx);
+       if (ignore_locality) {
+               start = 0;
+       } else if (xfs_bmap_adjacent(ap)) {
+               start = xfs_rtb_to_rtx(mp, ap->blkno);
+       } else if (ap->eof && ap->offset == 0) {
+               /*
+                * If it's an allocation to an empty file at offset 0, pick an
+                * extent that will space things out in the rt area.
+                */
+               error = xfs_rtpick_extent(mp, ap->tp, ralen, &start);
                if (error)
                        return error;
-               ap->blkno = xfs_rtx_to_rtb(mp, rtx);
        } else {
-               ap->blkno = 0;
+               start = 0;
        }
 
-       xfs_bmap_adjacent(ap);
-
-       /*
-        * Realtime allocation, done through xfs_rtallocate_extent.
-        */
-       if (ignore_locality)
-               rtx = 0;
-       else
-               rtx = xfs_rtb_to_rtx(mp, ap->blkno);
        raminlen = max_t(xfs_rtxlen_t, 1, xfs_extlen_to_rtxlen(mp, minlen));
-       error = xfs_rtallocate_extent(ap->tp, rtx, raminlen, ralen, &ralen,
+       error = xfs_rtallocate_extent(ap->tp, start, raminlen, ralen, &ralen,
                        ap->wasdel, prod, &rtx);
        if (error == -ENOSPC) {
                if (align > mp->m_sb.sb_rextsize) {
@@ -1499,7 +1494,7 @@ xfs_bmap_rtalloc(
                        goto retry;
                }
 
-               if (!ignore_locality && ap->blkno != 0) {
+               if (!ignore_locality && start != 0) {
                        /*
                         * If we can't allocate near a specific rt extent, try
                         * again without locality criteria.