[PATCH 09/19] xfs: cleanup picking the start extent hint in xfs_bmap_rtalloc

Christoph Hellwig
2023-12-14T06:35:07Z

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>
---
fs/xfs/xfs_rtalloc.c | 35 +++++++++++++++--------------------
1 file changed, 15 insertions(+), 20 deletions(-)

diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
index 158a631379378e..2ce3bcf4b84b76 100644
--- a/fs/xfs/xfs_rtalloc.c
+++ b/fs/xfs/xfs_rtalloc.c
@@ -1393,7 +1393,8 @@ 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 */
@@ -1454,30 +1455,24 @@ 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) {
@@ -1494,7 +1489,7 @@ 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.
--
2.39.2