If xfs_bmapi_write finds a delalloc extent at the requested range, it
tries to convert the entire delalloc extent to a real allocation.
But if the allocator cannot find a single free extent large enough to
cover the start block of the requested range, xfs_bmapi_write will
return 0 but leave *nimaps set to 0.
In that case we simply need to keep looping with the same startoffset_fsb
so that one of the following allocations will eventually reach the
requested range.
Note that this could affect any caller of xfs_bmapi_write that covers
an existing delayed allocation. As far as I can tell we do not have
any other such caller, though - the regular writeback path uses
xfs_bmapi_convert_delalloc to convert delayed allocations to real ones,
and direct I/O invalidates the page cache first.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
Changes since v1:
- update comments and the commit log
fs/xfs/xfs_bmap_util.c | 24 +++++++++++++-----------
1 file changed, 13 insertions(+), 11 deletions(-)
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index d85580b101ad8a..2458be8532c7aa 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -814,12 +814,10 @@ xfs_alloc_file_space(
{
xfs_mount_t *mp = ip->i_mount;
xfs_off_t count;
- xfs_filblks_t allocated_fsb;
xfs_filblks_t allocatesize_fsb;
xfs_extlen_t extsz, temp;
xfs_fileoff_t startoffset_fsb;
xfs_fileoff_t endoffset_fsb;
- int nimaps;
int rt;
xfs_trans_t *tp;
xfs_bmbt_irec_t imaps[1], *imapp;
@@ -842,7 +840,6 @@ xfs_alloc_file_space(
count = len;
imapp = &imaps[0];
- nimaps = 1;
startoffset_fsb = XFS_B_TO_FSBT(mp, offset);
endoffset_fsb = XFS_B_TO_FSB(mp, offset + count);
allocatesize_fsb = endoffset_fsb - startoffset_fsb;
@@ -853,6 +850,7 @@ xfs_alloc_file_space(
while (allocatesize_fsb && !error) {
xfs_fileoff_t s, e;
unsigned int dblocks, rblocks, resblks;
+ int nimaps = 1;
/*
* Determine space reservations for data/realtime.
@@ -918,15 +916,19 @@ xfs_alloc_file_space(
if (error)
break;
- allocated_fsb = imapp->br_blockcount;
-
- if (nimaps == 0) {
- error = -ENOSPC;
- break;
+ /*
+ * If the allocator cannot find a single free extent large
+ * enough to cover the start block of the requested range,
+ * xfs_bmapi_write will return 0 but leave *nimaps set to 0.
+ *
+ * In that case we simply need to keep looping with the same
+ * startoffset_fsb so that one of the following allocations
+ * will eventually reach the requested range.
+ */
+ if (nimaps) {
+ startoffset_fsb += imapp->br_blockcount;
+ allocatesize_fsb -= imapp->br_blockcount;
}
-
- startoffset_fsb += allocated_fsb;
- allocatesize_fsb -= allocated_fsb;
}
return error;
--
2.39.2
