[libvirt] [PATCHv2 09/16] storage: don't require caller to pre-allocate metadata struct
Laine Stump
laine at laine.org
Tue Oct 16 14:48:00 UTC 2012
On 10/13/2012 06:00 PM, Eric Blake wrote:
> Requiring pre-allocation was an unusual idiom. It allowed iteration
> over the backing chain to use fewer mallocs, but made one-shot
> clients harder to read. Also, this makes it easier for a future
> patch to move away from opening fds on every iteration over the chain.
>
> * src/util/storage_file.h (virStorageFileGetMetadataFromFD): Alter
> signature.
> * src/util/storage_file.c (virStorageFileGetMetadataFromFD): Allocate
> return value.
> (virStorageFileGetMetadata): Update clients.
> * src/conf/domain_conf.c (virDomainDiskDefForeachPath): Likewise.
> * src/qemu/qemu_driver.c (qemuDomainGetBlockInfo): Likewise.
> * src/storage/storage_backend_fs.c (virStorageBackendProbeTarget):
> Likewise.
> ---
> src/conf/domain_conf.c | 11 ++++------
> src/qemu/qemu_driver.c | 9 +-------
> src/storage/storage_backend_fs.c | 12 +++-------
> src/util/storage_file.c | 47 +++++++++++++++++++---------------------
> src/util/storage_file.h | 7 +++---
> 5 files changed, 33 insertions(+), 53 deletions(-)
>
> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> index acf1904..a1d5a1a 100644
> --- a/src/conf/domain_conf.c
> +++ b/src/conf/domain_conf.c
> @@ -14644,16 +14644,11 @@ int virDomainDiskDefForeachPath(virDomainDiskDefPtr disk,
> int ret = -1;
> size_t depth = 0;
> char *nextpath = NULL;
> - virStorageFileMetadata *meta;
> + virStorageFileMetadata *meta = NULL;
>
> if (!disk->src || disk->type == VIR_DOMAIN_DISK_TYPE_NETWORK)
> return 0;
>
> - if (VIR_ALLOC(meta) < 0) {
> - virReportOOMError();
> - return ret;
> - }
> -
> if (disk->format > 0) {
> format = disk->format;
> } else {
> @@ -14696,7 +14691,7 @@ int virDomainDiskDefForeachPath(virDomainDiskDefPtr disk,
> }
> }
>
> - if (virStorageFileGetMetadataFromFD(path, fd, format, meta) < 0) {
> + if (!(meta = virStorageFileGetMetadataFromFD(path, fd, format))) {
> VIR_FORCE_CLOSE(fd);
> goto cleanup;
> }
> @@ -14730,6 +14725,8 @@ int virDomainDiskDefForeachPath(virDomainDiskDefPtr disk,
> /* Allow probing for image formats that are safe */
> if (format == VIR_STORAGE_FILE_AUTO_SAFE)
> format = VIR_STORAGE_FILE_AUTO;
> + virStorageFileFreeMetadata(meta);
> + meta = NULL;
> } while (nextpath);
>
> ret = 0;
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 4d1c63c..0e7665e 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -9202,14 +9202,7 @@ static int qemuDomainGetBlockInfo(virDomainPtr dom,
> }
> }
>
> - if (VIR_ALLOC(meta) < 0) {
> - virReportOOMError();
> - goto cleanup;
> - }
> -
> - if (virStorageFileGetMetadataFromFD(path, fd,
> - format,
> - meta) < 0)
> + if (!(meta = virStorageFileGetMetadataFromFD(path, fd, format)))
> goto cleanup;
>
> /* Get info for normal formats */
> diff --git a/src/storage/storage_backend_fs.c b/src/storage/storage_backend_fs.c
> index db19b87..cecc2d2 100644
> --- a/src/storage/storage_backend_fs.c
> +++ b/src/storage/storage_backend_fs.c
> @@ -68,12 +68,7 @@ virStorageBackendProbeTarget(virStorageVolTargetPtr target,
> {
> int fd = -1;
> int ret = -1;
> - virStorageFileMetadata *meta;
> -
> - if (VIR_ALLOC(meta) < 0) {
> - virReportOOMError();
> - return ret;
> - }
> + virStorageFileMetadata *meta = NULL;
>
> *backingStore = NULL;
> *backingStoreFormat = VIR_STORAGE_FILE_AUTO;
> @@ -96,9 +91,8 @@ virStorageBackendProbeTarget(virStorageVolTargetPtr target,
> goto error;
> }
>
> - if (virStorageFileGetMetadataFromFD(target->path, fd,
> - target->format,
> - meta) < 0) {
> + if (!(meta = virStorageFileGetMetadataFromFD(target->path, fd,
> + target->format))) {
> ret = -1;
> goto error;
> }
> diff --git a/src/util/storage_file.c b/src/util/storage_file.c
> index 0f879bd..5387f1e 100644
> --- a/src/util/storage_file.c
> +++ b/src/util/storage_file.c
> @@ -852,41 +852,43 @@ virStorageFileProbeFormat(const char *path)
> * backing store. Callers are advised against probing for the
> * backing store format in this case.
> *
> - * Caller MUST free @meta after use via virStorageFileFreeMetadata.
> + * Caller MUST free the result after use via virStorageFileFreeMetadata.
> */
> -int
> +virStorageFileMetadataPtr
> virStorageFileGetMetadataFromFD(const char *path,
> int fd,
> - int format,
> - virStorageFileMetadata *meta)
> + int format)
> {
> + virStorageFileMetadata *meta = NULL;
> unsigned char *head = NULL;
> ssize_t len = STORAGE_MAX_HEAD;
> - int ret = -1;
> + virStorageFileMetadata *ret = NULL;
> struct stat sb;
>
> - memset(meta, 0, sizeof(*meta));
> + if (VIR_ALLOC(meta) < 0) {
> + virReportOOMError();
> + return NULL;
> + }
>
> if (fstat(fd, &sb) < 0) {
> virReportSystemError(errno,
> _("cannot stat file '%s'"),
> path);
> - return -1;
> + goto cleanup;
> }
>
> - /* No header to probe for directories */
> - if (S_ISDIR(sb.st_mode)) {
> - return 0;
> - }
> + /* No header to probe for directories, but also no backing file */
> + if (S_ISDIR(sb.st_mode))
> + return meta;
>
> if (lseek(fd, 0, SEEK_SET) == (off_t)-1) {
> virReportSystemError(errno, _("cannot seek to start of '%s'"), path);
> - return -1;
> + goto cleanup;
> }
>
> if (VIR_ALLOC_N(head, len) < 0) {
> virReportOOMError();
> - return -1;
> + goto cleanup;
> }
>
> if ((len = read(fd, head, len)) < 0) {
> @@ -904,9 +906,13 @@ virStorageFileGetMetadataFromFD(const char *path,
> goto cleanup;
> }
>
> - ret = virStorageFileGetMetadataFromBuf(format, path, head, len, meta);
> + if (virStorageFileGetMetadataFromBuf(format, path, head, len, meta) < 0)
> + goto cleanup;
> + ret = meta;
> + meta = NULL;
>
> cleanup:
> + virStorageFileFreeMetadata(meta);
> VIR_FREE(head);
> return ret;
> }
> @@ -934,21 +940,12 @@ virStorageFileGetMetadataRecurse(const char *path, int format,
> return NULL;
> }
>
> - if (VIR_ALLOC(ret) < 0) {
> - virReportOOMError();
> - VIR_FORCE_CLOSE(fd);
> - return NULL;
> - }
> - if (virStorageFileGetMetadataFromFD(path, fd, format, ret) < 0) {
> - virStorageFileFreeMetadata(ret);
> - VIR_FORCE_CLOSE(fd);
> - return NULL;
> - }
> + ret = virStorageFileGetMetadataFromFD(path, fd, format);
>
> if (VIR_CLOSE(fd) < 0)
> virReportSystemError(errno, _("could not close file %s"), path);
>
> - if (ret->backingStoreIsFile) {
> + if (ret && ret->backingStoreIsFile) {
> if (ret->backingStoreFormat == VIR_STORAGE_FILE_AUTO && !allow_probe)
> ret->backingStoreFormat = VIR_STORAGE_FILE_RAW;
> else if (ret->backingStoreFormat == VIR_STORAGE_FILE_AUTO_SAFE)
> diff --git a/src/util/storage_file.h b/src/util/storage_file.h
> index 18dea6a..9a60451 100644
> --- a/src/util/storage_file.h
> +++ b/src/util/storage_file.h
> @@ -73,10 +73,9 @@ virStorageFileMetadataPtr virStorageFileGetMetadata(const char *path,
> int format,
> uid_t uid, gid_t gid,
> bool allow_probe);
> -int virStorageFileGetMetadataFromFD(const char *path,
> - int fd,
> - int format,
> - virStorageFileMetadata *meta);
> +virStorageFileMetadataPtr virStorageFileGetMetadataFromFD(const char *path,
> + int fd,
> + int format);
>
> void virStorageFileFreeMetadata(virStorageFileMetadataPtr meta);
>
Fairly mechanical and straighforward. ACK.
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