The current version of raw-posix always uses ioctl(FS_IOC_FIEMAP) if
FIEMAP is available; lseek with SEEK_HOLE/SEEK_DATA are not even
compiled in in this case. However, there may be implementations which
support the latter but not the former (e.g., NFSv4.2). In this case,
raw-posix should fall back to lseek with SEEK_HOLE/SEEK_DATA if FIEMAP
does not work.
Signed-off-by: Max Reitz <mre...@redhat.com>
---
As Linux does not yet implement NFSv4.2 (I don't even know whether the
specification is complete), I have no way of testing whether this
actually works for the proposed case. But as it doesn't break any of the
existing test cases, it should be fine.
---
block/raw-posix.c | 27 +++++++++++++++++++++------
1 file changed, 21 insertions(+), 6 deletions(-)
diff --git a/block/raw-posix.c b/block/raw-posix.c
index 3ce026d..e523633 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -146,6 +146,9 @@ typedef struct BDRVRawState {
bool has_discard:1;
bool has_write_zeroes:1;
bool discard_zeroes:1;
+#if defined CONFIG_FIEMAP && defined SEEK_HOLE && defined SEEK_DATA
+ bool use_seek_hole_data;
+#endif
} BDRVRawState;
typedef struct BDRVRawReopenState {
@@ -1291,6 +1294,7 @@ static int64_t coroutine_fn
raw_co_get_block_status(BlockDriverState *bs,
int64_t sector_num,
int nb_sectors, int *pnum)
{
+ BDRVRawState *s = bs->opaque;
off_t start, data, hole;
int64_t ret;
@@ -1303,22 +1307,31 @@ static int64_t coroutine_fn
raw_co_get_block_status(BlockDriverState *bs,
ret = BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID | start;
#ifdef CONFIG_FIEMAP
-
- BDRVRawState *s = bs->opaque;
struct {
struct fiemap fm;
struct fiemap_extent fe;
} f;
+#if defined SEEK_HOLE && defined SEEK_DATA
+ if (s->use_seek_hole_data) {
+ goto try_seek_hole_data;
+ }
+#endif
+
f.fm.fm_start = start;
f.fm.fm_length = (int64_t)nb_sectors * BDRV_SECTOR_SIZE;
f.fm.fm_flags = 0;
f.fm.fm_extent_count = 1;
f.fm.fm_reserved = 0;
if (ioctl(s->fd, FS_IOC_FIEMAP, &f) == -1) {
+#if defined SEEK_HOLE && defined SEEK_DATA
+ s->use_seek_hole_data = true;
+ goto try_seek_hole_data;
+#else
/* Assume everything is allocated. */
*pnum = nb_sectors;
return ret;
+#endif
}
if (f.fm.fm_mapped_extents == 0) {
@@ -1336,10 +1349,11 @@ static int64_t coroutine_fn
raw_co_get_block_status(BlockDriverState *bs,
}
}
-#elif defined SEEK_HOLE && defined SEEK_DATA
-
- BDRVRawState *s = bs->opaque;
+ goto done;
+#endif
+#if defined SEEK_HOLE && defined SEEK_DATA
+try_seek_hole_data:
hole = lseek(s->fd, start, SEEK_HOLE);
if (hole == -1) {
/* -ENXIO indicates that sector_num was past the end of the file.
@@ -1360,11 +1374,12 @@ static int64_t coroutine_fn
raw_co_get_block_status(BlockDriverState *bs,
data = lseek(s->fd, 0, SEEK_END);
}
}
-#else
+#elif !defined CONFIG_FIEMAP
data = 0;
hole = start + nb_sectors * BDRV_SECTOR_SIZE;
#endif
+done:
if (data <= start) {
/* On a data extent, compute sectors to the end of the extent. */
*pnum = MIN(nb_sectors, (hole - start) / BDRV_SECTOR_SIZE);
--
1.9.2
