In preparation for reuse of the existing delayed allocation code for COW
reservation, factor out the part of xfs_file_iomap_begin_delay()
responsible for existing extent lookup into a new helper. This patch
does not change behavior.
Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
---
fs/xfs/xfs_iomap.c | 72 ++++++++++++++++++++++++++++++++++++++++++------------
1 file changed, 57 insertions(+), 15 deletions(-)
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 4f46f49..0a4ef18 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -522,6 +522,48 @@ xfs_iomap_prealloc_size(
return alloc_blocks;
}
+/*
+ * Prepare to handle delayed allocation based on whether extents exist in the
+ * inode data and COW forks. If an existing data extent is shared, determine
+ * whether COW fork reservation is necessary.
+ *
+ * The 'found' parameter indicates whether a writable mapping was found. If the
+ * mapping is shared, a COW reservation is performed for the corresponding
+ * range.
+ */
+static int
+xfs_iomap_search_extents(
+ struct xfs_inode *ip,
+ xfs_fileoff_t offset_fsb,
+ xfs_fileoff_t end_fsb,
+ int *eof,
+ int *idx,
+ struct xfs_bmbt_irec *got,
+ bool *found) /* found usable extent */
+{
+ struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
+ int error = 0;
+
+ *found = false;
+
+ *eof = !xfs_iext_lookup_extent(ip, ifp, offset_fsb, idx, got);
+ if (*eof || got->br_startoff > offset_fsb)
+ return 0;
+
+ if (xfs_is_reflink_inode(ip)) {
+ bool shared;
+
+ xfs_trim_extent(got, offset_fsb, end_fsb - offset_fsb);
+ error = xfs_reflink_reserve_cow(ip, got, &shared);
+ if (error)
+ return error;
+ }
+
+ *found = true;
+
+ return error;
+}
+
static int
xfs_file_iomap_begin_delay(
struct inode *inode,
@@ -533,18 +575,22 @@ xfs_file_iomap_begin_delay(
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
- xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
+ xfs_fileoff_t offset_fsb;
+ xfs_fileoff_t end_fsb;
xfs_fileoff_t maxbytes_fsb =
XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
- xfs_fileoff_t end_fsb;
int error = 0, eof = 0;
struct xfs_bmbt_irec got;
xfs_extnum_t idx;
xfs_fsblock_t prealloc_blocks = 0;
+ bool found;
ASSERT(!XFS_IS_REALTIME_INODE(ip));
ASSERT(!xfs_get_extsz_hint(ip));
+ offset_fsb = XFS_B_TO_FSBT(mp, offset);
+ end_fsb = min(XFS_B_TO_FSB(mp, offset + count), maxbytes_fsb);
+
xfs_ilock(ip, XFS_ILOCK_EXCL);
if (unlikely(XFS_TEST_ERROR(
@@ -564,19 +610,15 @@ xfs_file_iomap_begin_delay(
goto out_unlock;
}
- eof = !xfs_iext_lookup_extent(ip, ifp, offset_fsb, &idx, &got);
- if (!eof && got.br_startoff <= offset_fsb) {
- if (xfs_is_reflink_inode(ip)) {
- bool shared;
-
- end_fsb = min(XFS_B_TO_FSB(mp, offset + count),
- maxbytes_fsb);
- xfs_trim_extent(&got, offset_fsb, end_fsb - offset_fsb);
- error = xfs_reflink_reserve_cow(ip, &got, &shared);
- if (error)
- goto out_unlock;
- }
-
+ /*
+ * Search for preexisting extents. If an existing data extent is shared,
+ * this will perform COW fork reservation.
+ */
+ error = xfs_iomap_search_extents(ip, offset_fsb, end_fsb, &eof, &idx,
+ &got, &found);
+ if (error)
+ goto out_unlock;
+ if (found) {
trace_xfs_iomap_found(ip, offset, count, 0, &got);
goto done;
}
--
2.7.4
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