[PATCH 46/50] xfs: use for_each_perag_wrap in xfs_filestream_pick_ag

Dave Chinner
2022-06-11T01:27:44Z

xfs_filestream_pick_ag() is now ready to rework to use
for_each_perag_wrap() for iterating the perags during the AG
selection scan.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/xfs_filestream.c | 101 ++++++++++++++++------------------------
1 file changed, 41 insertions(+), 60 deletions(-)

diff --git a/fs/xfs/xfs_filestream.c b/fs/xfs/xfs_filestream.c
index 99013a9d3361..7b540898062e 100644
--- a/fs/xfs/xfs_filestream.c
+++ b/fs/xfs/xfs_filestream.c
@@ -83,9 +83,9 @@ xfs_filestream_pick_ag(
struct xfs_perag *max_pag = NULL;
xfs_extlen_t minlen = *longest;
xfs_extlen_t free = 0, minfree, maxfree = 0;
- xfs_agnumber_t startag = *agp;
- xfs_agnumber_t ag = startag;
- int err, trylock, nscan;
+ xfs_agnumber_t start_agno = *agp;
+ xfs_agnumber_t agno;
+ int err, trylock;

ASSERT(S_ISDIR(VFS_I(ip)->i_mode));

@@ -97,13 +97,9 @@ xfs_filestream_pick_ag(
/* For the first pass, don't sleep trying to init the per-AG. */
trylock = XFS_ALLOC_FLAG_TRYLOCK;

- for (nscan = 0; 1; nscan++) {
- trace_xfs_filestream_scan(mp, ip->i_ino, ag);
-
- err = 0;
- pag = xfs_perag_grab(mp, ag);
- if (!pag)
- goto next_ag;
+restart:
+ for_each_perag_wrap(mp, start_agno, agno, pag) {
+ trace_xfs_filestream_scan(mp, ip->i_ino, agno);
*longest = 0;
err = xfs_bmap_longest_free_extent(pag, NULL, longest);
if (err) {
@@ -111,6 +107,7 @@ xfs_filestream_pick_ag(
if (err != -EAGAIN)
break;
/* Couldn't lock the AGF, skip this AG. */
+ err = 0;
goto next_ag;
}

@@ -129,77 +126,61 @@ xfs_filestream_pick_ag(
* loop, and it guards against two filestreams being established
* in the same AG as each other.
*/
- if (atomic_inc_return(&pag->pagf_fstrms) > 1) {
- atomic_dec(&pag->pagf_fstrms);
- xfs_perag_rele(pag);
- goto next_ag;
- }
-
- if (((minlen && *longest >= minlen) ||
- (!minlen && pag->pagf_freeblks >= minfree)) &&
- (!xfs_perag_prefers_metadata(pag) ||
- !(flags & XFS_PICK_USERDATA) ||
- (flags & XFS_PICK_LOWSPACE))) {
-
- /* Break out, retaining the reference on the AG. */
- free = pag->pagf_freeblks;
- break;
+ if (atomic_inc_return(&pag->pagf_fstrms) <= 1) {
+ if (((minlen && *longest >= minlen) ||
+ (!minlen && pag->pagf_freeblks >= minfree)) &&
+ (!xfs_perag_prefers_metadata(pag) ||
+ !(flags & XFS_PICK_USERDATA) ||
+ (flags & XFS_PICK_LOWSPACE))) {
+ /* Break out, retaining the reference on the AG. */
+ free = pag->pagf_freeblks;
+ break;
+ }
}

/* Drop the reference on this AG, it's not usable. */
atomic_dec(&pag->pagf_fstrms);
-next_ag:
- /* Move to the next AG, wrapping to AG 0 if necessary. */
- if (++ag >= mp->m_sb.sb_agcount)
- ag = 0;
+ }

- /* If a full pass of the AGs hasn't been done yet, continue. */
- if (ag != startag)
- continue;
+ if (err) {
+ xfs_perag_rele(pag);
+ if (max_pag)
+ xfs_perag_rele(max_pag);
+ return err;
+ }

+ if (!pag) {
/* Allow sleeping in xfs_alloc_read_agf() on the 2nd pass. */
- if (trylock != 0) {
+ if (trylock) {
trylock = 0;
- continue;
+ goto restart;
}

/* Finally, if lowspace wasn't set, set it for the 3rd pass. */
if (!(flags & XFS_PICK_LOWSPACE)) {
flags |= XFS_PICK_LOWSPACE;
- continue;
+ goto restart;
}

/*
- * Take the AG with the most free space, regardless of whether
- * it's already in use by another filestream.
+ * No unassociated AGs are available, so select the AG with the
+ * most free space, regardless of whether it's already in use by
+ * another filestream. It none suit, return NULLAGNUMBER.
*/
- if (max_pag) {
- pag = max_pag;
- atomic_inc(&pag->pagf_fstrms);
- free = maxfree;
- break;
+ if (!max_pag) {
+ *agp = NULLAGNUMBER;
+ trace_xfs_filestream_pick(ip, *agp, free, 0);
+ return 0;
}
-
- /* take AG 0 if none matched */
- trace_xfs_filestream_pick(ip, *agp, free, nscan);
- *agp = 0;
- return 0;
- }
-
- trace_xfs_filestream_pick(ip, pag ? pag->pag_agno : NULLAGNUMBER,
- free, nscan);
-
- if (max_pag)
+ pag = max_pag;
+ free = maxfree;
+ atomic_inc(&pag->pagf_fstrms);
+ } else if (max_pag) {
xfs_perag_rele(max_pag);
-
- if (err)
- return err;
-
- if (!pag) {
- *agp = NULLAGNUMBER;
- return 0;
}

+ trace_xfs_filestream_pick(ip, pag->pag_agno, free, 0);
+
err = -ENOMEM;
item = kmem_alloc(sizeof(*item), KM_MAYFAIL);
if (!item)
--
2.35.1