diff options
| -rw-r--r-- | block/file-posix.c | 61 |
1 files changed, 50 insertions, 11 deletions
diff --git a/block/file-posix.c b/block/file-posix.c index deefd6efac..59154ea936 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -1624,11 +1624,31 @@ static void raw_close(BlockDriverState *bs) } } +/** + * Truncates the given regular file @fd to @offset and, when growing, fills the + * new space according to @prealloc. + * + * Returns: 0 on success, -errno on failure. + */ static int raw_regular_truncate(int fd, int64_t offset, PreallocMode prealloc, Error **errp) { int result = 0; - char *buf; + int64_t current_length = 0; + char *buf = NULL; + struct stat st; + + if (fstat(fd, &st) < 0) { + result = -errno; + error_setg_errno(errp, -result, "Could not stat file"); + return result; + } + + current_length = st.st_size; + if (current_length > offset && prealloc != PREALLOC_MODE_OFF) { + error_setg(errp, "Cannot use preallocation for shrinking files"); + return -ENOTSUP; + } switch (prealloc) { #ifdef CONFIG_POSIX_FALLOCATE @@ -1638,17 +1658,17 @@ static int raw_regular_truncate(int fd, int64_t offset, PreallocMode prealloc, * file systems that do not support fallocate(), trying to check if a * block is allocated before allocating it, so don't do that here. */ - result = -posix_fallocate(fd, 0, offset); + result = -posix_fallocate(fd, current_length, offset - current_length); if (result != 0) { /* posix_fallocate() doesn't set errno. */ error_setg_errno(errp, -result, - "Could not preallocate data for the new file"); + "Could not preallocate new data"); } - return result; + goto out; #endif case PREALLOC_MODE_FULL: { - int64_t num = 0, left = offset; + int64_t num = 0, left = offset - current_length; /* * Knowing the final size from the beginning could allow the file @@ -1658,19 +1678,27 @@ static int raw_regular_truncate(int fd, int64_t offset, PreallocMode prealloc, if (ftruncate(fd, offset) != 0) { result = -errno; error_setg_errno(errp, -result, "Could not resize file"); - return result; + goto out; } buf = g_malloc0(65536); + result = lseek(fd, current_length, SEEK_SET); + if (result < 0) { + result = -errno; + error_setg_errno(errp, -result, + "Failed to seek to the old end of file"); + goto out; + } + while (left > 0) { num = MIN(left, 65536); result = write(fd, buf, num); if (result < 0) { result = -errno; error_setg_errno(errp, -result, - "Could not write to the new file"); - break; + "Could not write zeros for preallocation"); + goto out; } left -= result; } @@ -1679,11 +1707,11 @@ static int raw_regular_truncate(int fd, int64_t offset, PreallocMode prealloc, if (result < 0) { result = -errno; error_setg_errno(errp, -result, - "Could not flush new file to disk"); + "Could not flush file to disk"); + goto out; } } - g_free(buf); - return result; + goto out; } case PREALLOC_MODE_OFF: if (ftruncate(fd, offset) != 0) { @@ -1697,6 +1725,17 @@ static int raw_regular_truncate(int fd, int64_t offset, PreallocMode prealloc, PreallocMode_lookup[prealloc]); return result; } + +out: + if (result < 0) { + if (ftruncate(fd, current_length) < 0) { + error_report("Failed to restore old file length: %s", + strerror(errno)); + } + } + + g_free(buf); + return result; } static int raw_truncate(BlockDriverState *bs, int64_t offset, |