typedef struct BDRVGlusterState {
struct glfs *glfs;
struct glfs_fd *fd;
+ bool supports_seek_data;
} BDRVGlusterState;
typedef struct GlusterConf {
}
}
+/*
+ * Do SEEK_DATA/HOLE to detect if it is functional. Older broken versions of
+ * gfapi incorrectly return the current offset when SEEK_DATA/HOLE is used.
+ * - Corrected versions return -1 and set errno to EINVAL.
+ * - Versions that support SEEK_DATA/HOLE correctly, will return -1 and set
+ * errno to ENXIO when SEEK_DATA is called with a position of EOF.
+ */
+static bool qemu_gluster_test_seek(struct glfs_fd *fd)
+{
+ off_t ret, eof;
+
+ eof = glfs_lseek(fd, 0, SEEK_END);
+ if (eof < 0) {
+ /* this should never occur */
+ return false;
+ }
+
+ /* this should always fail with ENXIO if SEEK_DATA is supported */
+ ret = glfs_lseek(fd, eof, SEEK_DATA);
+ return (ret < 0) && (errno == ENXIO);
+}
+
static int qemu_gluster_open(BlockDriverState *bs, QDict *options,
int bdrv_flags, Error **errp)
{
ret = -errno;
}
+ s->supports_seek_data = qemu_gluster_test_seek(s->fd);
+
out:
qemu_opts_del(opts);
qemu_gluster_gconf_free(gconf);
return 0;
}
+/*
+ * Find allocation range in @bs around offset @start.
+ * May change underlying file descriptor's file offset.
+ * If @start is not in a hole, store @start in @data, and the
+ * beginning of the next hole in @hole, and return 0.
+ * If @start is in a non-trailing hole, store @start in @hole and the
+ * beginning of the next non-hole in @data, and return 0.
+ * If @start is in a trailing hole or beyond EOF, return -ENXIO.
+ * If we can't find out, return a negative errno other than -ENXIO.
+ *
+ * (Shamefully copied from raw-posix.c, only miniscule adaptions.)
+ */
+static int find_allocation(BlockDriverState *bs, off_t start,
+ off_t *data, off_t *hole)
+{
+ BDRVGlusterState *s = bs->opaque;
+ off_t offs;
+
+ if (!s->supports_seek_data) {
+ return -ENOTSUP;
+ }
+
+ /*
+ * SEEK_DATA cases:
+ * D1. offs == start: start is in data
+ * D2. offs > start: start is in a hole, next data at offs
+ * D3. offs < 0, errno = ENXIO: either start is in a trailing hole
+ * or start is beyond EOF
+ * If the latter happens, the file has been truncated behind
+ * our back since we opened it. All bets are off then.
+ * Treating like a trailing hole is simplest.
+ * D4. offs < 0, errno != ENXIO: we learned nothing
+ */
+ offs = glfs_lseek(s->fd, start, SEEK_DATA);
+ if (offs < 0) {
+ return -errno; /* D3 or D4 */
+ }
+ assert(offs >= start);
+
+ if (offs > start) {
+ /* D2: in hole, next data at offs */
+ *hole = start;
+ *data = offs;
+ return 0;
+ }
+
+ /* D1: in data, end not yet known */
+
+ /*
+ * SEEK_HOLE cases:
+ * H1. offs == start: start is in a hole
+ * If this happens here, a hole has been dug behind our back
+ * since the previous lseek().
+ * H2. offs > start: either start is in data, next hole at offs,
+ * or start is in trailing hole, EOF at offs
+ * Linux treats trailing holes like any other hole: offs ==
+ * start. Solaris seeks to EOF instead: offs > start (blech).
+ * If that happens here, a hole has been dug behind our back
+ * since the previous lseek().
+ * H3. offs < 0, errno = ENXIO: start is beyond EOF
+ * If this happens, the file has been truncated behind our
+ * back since we opened it. Treat it like a trailing hole.
+ * H4. offs < 0, errno != ENXIO: we learned nothing
+ * Pretend we know nothing at all, i.e. "forget" about D1.
+ */
+ offs = glfs_lseek(s->fd, start, SEEK_HOLE);
+ if (offs < 0) {
+ return -errno; /* D1 and (H3 or H4) */
+ }
+ assert(offs >= start);
+
+ if (offs > start) {
+ /*
+ * D1 and H2: either in data, next hole at offs, or it was in
+ * data but is now in a trailing hole. In the latter case,
+ * all bets are off. Treating it as if it there was data all
+ * the way to EOF is safe, so simply do that.
+ */
+ *data = start;
+ *hole = offs;
+ return 0;
+ }
+
+ /* D1 and H1 */
+ return -EBUSY;
+}
+
+/*
+ * Returns the allocation status of the specified sectors.
+ *
+ * If 'sector_num' is beyond the end of the disk image the return value is 0
+ * and 'pnum' is set to 0.
+ *
+ * 'pnum' is set to the number of sectors (including and immediately following
+ * the specified sector) that are known to be in the same
+ * allocated/unallocated state.
+ *
+ * 'nb_sectors' is the max value 'pnum' should be set to. If nb_sectors goes
+ * beyond the end of the disk image it will be clamped.
+ *
+ * (Based on raw_co_get_block_status() from raw-posix.c.)
+ */
+static int64_t coroutine_fn qemu_gluster_co_get_block_status(
+ BlockDriverState *bs, int64_t sector_num, int nb_sectors, int *pnum,
+ BlockDriverState **file)
+{
+ BDRVGlusterState *s = bs->opaque;
+ off_t start, data = 0, hole = 0;
+ int64_t total_size;
+ int ret = -EINVAL;
+
+ if (!s->fd) {
+ return ret;
+ }
+
+ start = sector_num * BDRV_SECTOR_SIZE;
+ total_size = bdrv_getlength(bs);
+ if (total_size < 0) {
+ return total_size;
+ } else if (start >= total_size) {
+ *pnum = 0;
+ return 0;
+ } else if (start + nb_sectors * BDRV_SECTOR_SIZE > total_size) {
+ nb_sectors = DIV_ROUND_UP(total_size - start, BDRV_SECTOR_SIZE);
+ }
+
+ ret = find_allocation(bs, start, &data, &hole);
+ if (ret == -ENXIO) {
+ /* Trailing hole */
+ *pnum = nb_sectors;
+ ret = BDRV_BLOCK_ZERO;
+ } else if (ret < 0) {
+ /* No info available, so pretend there are no holes */
+ *pnum = nb_sectors;
+ ret = BDRV_BLOCK_DATA;
+ } else if (data == start) {
+ /* On a data extent, compute sectors to the end of the extent,
+ * possibly including a partial sector at EOF. */
+ *pnum = MIN(nb_sectors, DIV_ROUND_UP(hole - start, BDRV_SECTOR_SIZE));
+ ret = BDRV_BLOCK_DATA;
+ } else {
+ /* On a hole, compute sectors to the beginning of the next extent. */
+ assert(hole == start);
+ *pnum = MIN(nb_sectors, (data - start) / BDRV_SECTOR_SIZE);
+ ret = BDRV_BLOCK_ZERO;
+ }
+
+ *file = bs;
+
+ return ret | BDRV_BLOCK_OFFSET_VALID | start;
+}
+
+
static QemuOptsList qemu_gluster_create_opts = {
.name = "qemu-gluster-create-opts",
.head = QTAILQ_HEAD_INITIALIZER(qemu_gluster_create_opts.head),
#ifdef CONFIG_GLUSTERFS_ZEROFILL
.bdrv_co_pwrite_zeroes = qemu_gluster_co_pwrite_zeroes,
#endif
+ .bdrv_co_get_block_status = qemu_gluster_co_get_block_status,
.create_opts = &qemu_gluster_create_opts,
};
#ifdef CONFIG_GLUSTERFS_ZEROFILL
.bdrv_co_pwrite_zeroes = qemu_gluster_co_pwrite_zeroes,
#endif
+ .bdrv_co_get_block_status = qemu_gluster_co_get_block_status,
.create_opts = &qemu_gluster_create_opts,
};
#ifdef CONFIG_GLUSTERFS_ZEROFILL
.bdrv_co_pwrite_zeroes = qemu_gluster_co_pwrite_zeroes,
#endif
+ .bdrv_co_get_block_status = qemu_gluster_co_get_block_status,
.create_opts = &qemu_gluster_create_opts,
};
#ifdef CONFIG_GLUSTERFS_ZEROFILL
.bdrv_co_pwrite_zeroes = qemu_gluster_co_pwrite_zeroes,
#endif
+ .bdrv_co_get_block_status = qemu_gluster_co_get_block_status,
.create_opts = &qemu_gluster_create_opts,
};
projects / sdk / emulator / qemu.git / commitdiff