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authorPeter Maydell <peter.maydell@linaro.org>2014-11-18 13:43:37 +0000
committerPeter Maydell <peter.maydell@linaro.org>2014-11-18 13:43:37 +0000
commit1ab8f867ef2ef0aa259e0e0d1040d67350af1bec (patch)
treee93593083dab1e3016377fbb4bc187fe8ab12efe
parentea5b201a0acfb4c3029afd4e7999b4278e1351d4 (diff)
parent098ffa6674a82ceac0e3ccb3a8a5bf6ca44adcd5 (diff)
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Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging
Block patches for 2.2.0-rc2 # gpg: Signature made Tue 18 Nov 2014 11:32:55 GMT using RSA key ID C88F2FD6 # gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>" * remotes/kevin/tags/for-upstream: block/raw-posix: Catch fsync() errors block/raw-posix: Only sync after successful preallocation block/raw-posix: Fix preallocating write() loop raw-posix: The SEEK_HOLE code is flawed, rewrite it raw-posix: SEEK_HOLE suffices, get rid of FIEMAP raw-posix: Fix comment for raw_co_get_block_status() Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
-rw-r--r--block/raw-posix.c173
1 files changed, 91 insertions, 82 deletions
diff --git a/block/raw-posix.c b/block/raw-posix.c
index e100ae2..b1af77e 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -60,9 +60,6 @@
#define FS_NOCOW_FL 0x00800000 /* Do not cow file */
#endif
#endif
-#ifdef CONFIG_FIEMAP
-#include <linux/fiemap.h>
-#endif
#ifdef CONFIG_FALLOCATE_PUNCH_HOLE
#include <linux/falloc.h>
#endif
@@ -151,9 +148,6 @@ typedef struct BDRVRawState {
bool has_write_zeroes:1;
bool discard_zeroes:1;
bool needs_alignment;
-#ifdef CONFIG_FIEMAP
- bool skip_fiemap;
-#endif
} BDRVRawState;
typedef struct BDRVRawReopenState {
@@ -1457,9 +1451,16 @@ static int raw_create(const char *filename, QemuOpts *opts, Error **errp)
"Could not write to the new file");
break;
}
- left -= num;
+ left -= result;
+ }
+ if (result >= 0) {
+ result = fsync(fd);
+ if (result < 0) {
+ result = -errno;
+ error_setg_errno(errp, -result,
+ "Could not flush new file to disk");
+ }
}
- fsync(fd);
g_free(buf);
break;
}
@@ -1481,83 +1482,93 @@ out:
return result;
}
-static int try_fiemap(BlockDriverState *bs, off_t start, off_t *data,
- off_t *hole, int nb_sectors)
+/*
+ * 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.
+ */
+static int find_allocation(BlockDriverState *bs, off_t start,
+ off_t *data, off_t *hole)
{
-#ifdef CONFIG_FIEMAP
+#if defined SEEK_HOLE && defined SEEK_DATA
BDRVRawState *s = bs->opaque;
- int ret = 0;
- struct {
- struct fiemap fm;
- struct fiemap_extent fe;
- } f;
+ off_t offs;
- if (s->skip_fiemap) {
- return -ENOTSUP;
- }
-
- f.fm.fm_start = start;
- f.fm.fm_length = (int64_t)nb_sectors * BDRV_SECTOR_SIZE;
- f.fm.fm_flags = FIEMAP_FLAG_SYNC;
- f.fm.fm_extent_count = 1;
- f.fm.fm_reserved = 0;
- if (ioctl(s->fd, FS_IOC_FIEMAP, &f) == -1) {
- s->skip_fiemap = true;
- return -errno;
+ /*
+ * 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 = lseek(s->fd, start, SEEK_DATA);
+ if (offs < 0) {
+ return -errno; /* D3 or D4 */
}
+ assert(offs >= start);
- if (f.fm.fm_mapped_extents == 0) {
- /* No extents found, data is beyond f.fm.fm_start + f.fm.fm_length.
- * f.fm.fm_start + f.fm.fm_length must be clamped to the file size!
- */
- off_t length = lseek(s->fd, 0, SEEK_END);
- *hole = f.fm.fm_start;
- *data = MIN(f.fm.fm_start + f.fm.fm_length, length);
- } else {
- *data = f.fe.fe_logical;
- *hole = f.fe.fe_logical + f.fe.fe_length;
- if (f.fe.fe_flags & FIEMAP_EXTENT_UNWRITTEN) {
- ret |= BDRV_BLOCK_ZERO;
- }
+ if (offs > start) {
+ /* D2: in hole, next data at offs */
+ *hole = start;
+ *data = offs;
+ return 0;
}
- return ret;
-#else
- return -ENOTSUP;
-#endif
-}
-
-static int try_seek_hole(BlockDriverState *bs, off_t start, off_t *data,
- off_t *hole)
-{
-#if defined SEEK_HOLE && defined SEEK_DATA
- BDRVRawState *s = bs->opaque;
+ /* D1: in data, end not yet known */
- *hole = lseek(s->fd, start, SEEK_HOLE);
- if (*hole == -1) {
- return -errno;
+ /*
+ * 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 = lseek(s->fd, start, SEEK_HOLE);
+ if (offs < 0) {
+ return -errno; /* D1 and (H3 or H4) */
}
+ assert(offs >= start);
- if (*hole > 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;
- } else {
- /* On a hole. We need another syscall to find its end. */
- *data = lseek(s->fd, start, SEEK_DATA);
- if (*data == -1) {
- *data = lseek(s->fd, 0, SEEK_END);
- }
+ *hole = offs;
+ return 0;
}
- return 0;
+ /* D1 and H1 */
+ return -EBUSY;
#else
return -ENOTSUP;
#endif
}
/*
- * Returns true iff the specified sector is present in the disk image. Drivers
- * not implementing the functionality are assumed to not support backing files,
- * hence all their sectors are reported as allocated.
+ * 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.
@@ -1593,28 +1604,26 @@ static int64_t coroutine_fn raw_co_get_block_status(BlockDriverState *bs,
nb_sectors = DIV_ROUND_UP(total_size - start, BDRV_SECTOR_SIZE);
}
- ret = try_seek_hole(bs, start, &data, &hole);
- if (ret < 0) {
- ret = try_fiemap(bs, start, &data, &hole, nb_sectors);
- if (ret < 0) {
- /* Assume everything is allocated. */
- data = 0;
- hole = start + nb_sectors * BDRV_SECTOR_SIZE;
- ret = 0;
- }
- }
-
- assert(ret >= 0);
-
- if (data <= start) {
+ 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. */
*pnum = MIN(nb_sectors, (hole - start) / BDRV_SECTOR_SIZE);
- return ret | BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID | start;
+ 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);
- return ret | BDRV_BLOCK_ZERO | BDRV_BLOCK_OFFSET_VALID | start;
+ ret = BDRV_BLOCK_ZERO;
}
+ return ret | BDRV_BLOCK_OFFSET_VALID | start;
}
static coroutine_fn BlockAIOCB *raw_aio_discard(BlockDriverState *bs,