xfs_seek_hole() refinement with hole searching from page cache for unwritten extent.
Signed-off-by: Jie Liu <jeff.liu@xxxxxxxxxx>
Reviewed-by: Mark Tinguely <tinguely@xxxxxxx>
Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx>
---
fs/xfs/xfs_file.c | 78 +++++++++++++++++++++++++++++++++++++++++++++-------
1 files changed, 67 insertions(+), 11 deletions(-)
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 3f91074..1eaeb8b 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1289,9 +1289,9 @@ xfs_seek_hole(
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
loff_t uninitialized_var(offset);
- loff_t holeoff;
xfs_fsize_t isize;
xfs_fileoff_t fsbno;
+ xfs_filblks_t end;
uint lock;
int error;
@@ -1307,21 +1307,77 @@ xfs_seek_hole(
}
fsbno = XFS_B_TO_FSBT(mp, start);
- error = xfs_bmap_first_unused(NULL, ip, 1, &fsbno, XFS_DATA_FORK);
- if (error)
- goto out_unlock;
+ end = XFS_B_TO_FSB(mp, isize);
+
+ for (;;) {
+ struct xfs_bmbt_irec map[2];
+ int nmap = 2;
+ unsigned int i;
+
+ error = xfs_bmapi_read(ip, fsbno, end - fsbno, map, &nmap,
+ XFS_BMAPI_ENTIRE);
+ if (error)
+ goto out_unlock;
+
+ /* No extents at given offset, must be beyond EOF */
+ if (nmap == 0) {
+ error = ENXIO;
+ goto out_unlock;
+ }
+
+ for (i = 0; i < nmap; i++) {
+ offset = max_t(loff_t, start,
+ XFS_FSB_TO_B(mp, map[i].br_startoff));
+
+ /* Landed in a hole */
+ if (map[i].br_startblock == HOLESTARTBLOCK)
+ goto out;
+
+ /*
+ * Landed in an unwritten extent, try to search hole
+ * from page cache.
+ */
+ if (map[i].br_state == XFS_EXT_UNWRITTEN) {
+ if (xfs_find_get_desired_pgoff(inode, &map[i],
+ HOLE_OFF, &offset))
+ goto out;
+ }
+ }
- holeoff = XFS_FSB_TO_B(mp, fsbno);
- if (holeoff <= start)
- offset = start;
- else {
/*
- * xfs_bmap_first_unused() could return a value bigger than
- * isize if there are no more holes past the supplied offset.
+ * map[0] contains data or its unwritten but contains
+ * data in page cache, probably means that we are
+ * reading after EOF. We should fix offset to point
+ * to the end of the file(i.e., there is an implicit
+ * hole at the end of any file).
*/
- offset = min_t(loff_t, holeoff, isize);
+ if (nmap == 1) {
+ offset = isize;
+ break;
+ }
+
+ ASSERT(i > 1);
+
+ /*
+ * Both mappings contains data, proceed to the next round of
+ * search if the current reading offset not beyond or hit EOF.
+ */
+ fsbno = map[i - 1].br_startoff + map[i - 1].br_blockcount;
+ start = XFS_FSB_TO_B(mp, fsbno);
+ if (start >= isize) {
+ offset = isize;
+ break;
+ }
}
+out:
+ /*
+ * At this point, we must have found a hole. However, the returned
+ * offset may be bigger than the file size as it may be aligned to
+ * page boundary for unwritten extents, we need to deal with this
+ * situation in particular.
+ */
+ offset = min_t(loff_t, offset, isize);
if (offset != file->f_pos)
file->f_pos = offset;
--
1.7.4.1
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