> + /*
> + * if we don't find an overlapping extent, trim the range we need to
> + * allocate to fit the hole we found.
> + */
Please capitalize the first letter in each sentence.
> + *shared = true;
> + if (isnullstartblock(got.br_startblock)) {
> + xfs_trim_extent(imap, got.br_startoff, got.br_blockcount);
> + return 0;
> + }
Taken out of the context of the bigger function this conditional
could really use a comment as well.
> + } while (tp);
This looks a little odd as tp will always be true if we reach this
point. I'd suggest to switch to a do { } while (1) or for (;;) style
loop.
Alternatively we could just skip the loop entirely now that we have
the lookup + trim helper. Untested patch below:
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 38f405415b88..79e2279d8e15 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -352,6 +352,47 @@ xfs_reflink_convert_cow(
return error;
}
+/*
+ * Find the extent that maps the given range in the COW fork. Even if the extent
+ * is not shared we might have a preallocation for it in the COW fork. If so we
+ * use it that rather than trigger a new allocation.
+ */
+static int
+find_trim_cow_extent(
+ struct xfs_inode *ip,
+ struct xfs_bmbt_irec *imap,
+ bool *shared,
+ bool *found)
+{
+ xfs_fileoff_t offset_fsb = imap->br_startoff;
+ xfs_filblks_t count_fsb = imap->br_blockcount;
+ struct xfs_iext_cursor icur;
+ struct xfs_bmbt_irec got;
+ bool trimmed;
+
+ *found = false;
+
+ /*
+ * If we don't find an overlapping extent, trim the range we need to
+ * allocate to fit the hole we found.
+ */
+ if (!xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &got) ||
+ got.br_startoff > offset_fsb)
+ return xfs_reflink_trim_around_shared(ip, imap, shared, &trimmed);
+
+ *shared = true;
+ if (isnullstartblock(got.br_startblock)) {
+ xfs_trim_extent(imap, got.br_startoff, got.br_blockcount);
+ return 0;
+ }
+
+ /* real extent found - no need to allocate */
+ xfs_trim_extent(&got, offset_fsb, count_fsb);
+ *imap = got;
+ *found = true;
+ return 0;
+}
+
/* Allocate all CoW reservations covering a range of blocks in a file. */
int
xfs_reflink_allocate_cow(
@@ -363,78 +404,62 @@ xfs_reflink_allocate_cow(
struct xfs_mount *mp = ip->i_mount;
xfs_fileoff_t offset_fsb = imap->br_startoff;
xfs_filblks_t count_fsb = imap->br_blockcount;
- struct xfs_bmbt_irec got;
- struct xfs_trans *tp = NULL;
+ struct xfs_trans *tp;
int nimaps, error = 0;
- bool trimmed;
+ bool found;
xfs_filblks_t resaligned;
xfs_extlen_t resblks = 0;
- struct xfs_iext_cursor icur;
-retry:
- ASSERT(xfs_is_reflink_inode(ip));
ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+ ASSERT(xfs_is_reflink_inode(ip));
- /*
- * Even if the extent is not shared we might have a preallocation for
- * it in the COW fork. If so use it.
- */
- if (xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &got) &&
- got.br_startoff <= offset_fsb) {
- *shared = true;
-
- /* If we have a real allocation in the COW fork we're done. */
- if (!isnullstartblock(got.br_startblock)) {
- xfs_trim_extent(&got, offset_fsb, count_fsb);
- *imap = got;
- goto convert;
- }
+ error = find_trim_cow_extent(ip, imap, shared, &found);
+ if (error || !*shared)
+ return error;
+ if (found)
+ goto convert;
- xfs_trim_extent(imap, got.br_startoff, got.br_blockcount);
- } else {
- error = xfs_reflink_trim_around_shared(ip, imap, shared, &trimmed);
- if (error || !*shared)
- goto out;
- }
+ resaligned = xfs_aligned_fsb_count(imap->br_startoff,
+ imap->br_blockcount, xfs_get_cowextsz_hint(ip));
+ resblks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
- if (!tp) {
- resaligned = xfs_aligned_fsb_count(imap->br_startoff,
- imap->br_blockcount, xfs_get_cowextsz_hint(ip));
- resblks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
+ xfs_iunlock(ip, *lockmode);
+ error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, 0, &tp);
+ *lockmode = XFS_ILOCK_EXCL;
+ xfs_ilock(ip, *lockmode);
- xfs_iunlock(ip, *lockmode);
- error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, 0, &tp);
- *lockmode = XFS_ILOCK_EXCL;
- xfs_ilock(ip, *lockmode);
+ if (error)
+ return error;
- if (error)
- return error;
+ error = xfs_qm_dqattach_locked(ip, false);
+ if (error)
+ goto out_trans_cancel;
- error = xfs_qm_dqattach_locked(ip, false);
- if (error)
- goto out;
- goto retry;
+ /* check for an overlapping extent again no that we dropped the ilock */
+ error = find_trim_cow_extent(ip, imap, shared, &found);
+ if (error || !*shared)
+ goto out_trans_cancel;
+ if (found) {
+ xfs_trans_cancel(tp);
+ goto convert;
}
error = xfs_trans_reserve_quota_nblks(tp, ip, resblks, 0,
XFS_QMOPT_RES_REGBLKS);
if (error)
- goto out;
+ goto out_trans_cancel;
xfs_trans_ijoin(tp, ip, 0);
- nimaps = 1;
-
/* Allocate the entire reservation as unwritten blocks. */
+ nimaps = 1;
error = xfs_bmapi_write(tp, ip, imap->br_startoff, imap->br_blockcount,
XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC,
resblks, imap, &nimaps);
if (error)
- goto out_trans_cancel;
+ goto out_unreserve;
xfs_inode_set_cowblocks_tag(ip);
-
- /* Finish up. */
error = xfs_trans_commit(tp);
if (error)
return error;
@@ -447,12 +472,12 @@ xfs_reflink_allocate_cow(
return -ENOSPC;
convert:
return xfs_reflink_convert_cow_extent(ip, imap, offset_fsb, count_fsb);
-out_trans_cancel:
+
+out_unreserve:
xfs_trans_unreserve_quota_nblks(tp, ip, (long)resblks, 0,
XFS_QMOPT_RES_REGBLKS);
-out:
- if (tp)
- xfs_trans_cancel(tp);
+out_trans_cancel:
+ xfs_trans_cancel(tp);
return error;
}
