diff options
| -rw-r--r-- | block/raw-posix.c | 173 |
1 files changed, 91 insertions, 82 deletions
diff --git a/block/raw-posix.c b/block/raw-posix.c index e100ae2046..b1af77e47f 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, |