Similar to the openflags VIR_STORAGE_VOL_OPEN_NOERROR processing, if some read processing operation fails, check the readflags for the corresponding error flag being set. If so, rather then causing an error - use VIR_WARN to flag the error, but return -2 which some callers can use to perform specific actions. Use a new VIR_STORAGE_VOL_READ_NOERROR flag in a new VolReadErrorMode enum. Signed-off-by: John Ferlan <jferlan@xxxxxxxxxx> --- src/storage/storage_backend.c | 43 +++++++++++++++++++++++++++++++------------ src/storage/storage_backend.h | 9 +++++++++ 2 files changed, 40 insertions(+), 12 deletions(-) diff --git a/src/storage/storage_backend.c b/src/storage/storage_backend.c index 8eb5b04..c29b162 100644 --- a/src/storage/storage_backend.c +++ b/src/storage/storage_backend.c @@ -1393,14 +1393,17 @@ static struct diskType const disk_types[] = { * virStorageBackendDetectBlockVolFormatFD * @target: target definition ptr of volume to update * @fd: fd of storage volume to update, - * @readflags: unused + * @readflags: VolReadErrorMode flags to handle read error after open + * is successful, but read is not. * - * Returns 0 for success, -1 on a legitimate error condition + * Returns 0 for success, -1 on a legitimate error condition, -2 if + * the read error is desired to be ignored (along with appropriate + * VIR_WARN of the issue). */ static int virStorageBackendDetectBlockVolFormatFD(virStorageSourcePtr target, int fd, - unsigned int readflags ATTRIBUTE_UNUSED) + unsigned int readflags) { size_t i; off_t start; @@ -1419,10 +1422,16 @@ virStorageBackendDetectBlockVolFormatFD(virStorageSourcePtr target, } bytes = saferead(fd, buffer, sizeof(buffer)); if (bytes < 0) { - virReportSystemError(errno, - _("cannot read beginning of file '%s'"), - target->path); - return -1; + if (readflags & VIR_STORAGE_VOL_READ_NOERROR) { + VIR_WARN("ignoring failed saferead of file '%s'", + target->path); + return -2; + } else { + virReportSystemError(errno, + _("cannot read beginning of file '%s'"), + target->path); + return -1; + } } for (i = 0; disk_types[i].part_table_type != -1; i++) { @@ -1591,11 +1600,13 @@ virStorageBackendVolOpen(const char *path, struct stat *sb, * @target: target definition ptr of volume to update * @withBlockVolFormat: true if caller determined a block file * @openflags: various VolOpenCheckMode flags to handle errors on open - * @readflags: unused + * @readflags: VolReadErrorMode flags to handle read error after open + * is successful, but read is not. * * Returns 0 for success, -1 on a legitimate error condition, and -2 * if the openflags used VIR_STORAGE_VOL_OPEN_NOERROR and some sort of - * open error occurred. It is up to the caller to handle. + * open error occurred. It is up to the caller to handle. A -2 may also + * be returned if the caller passed a readflagsflag. */ int virStorageBackendUpdateVolTargetInfo(virStorageSourcePtr target, @@ -1630,8 +1641,16 @@ virStorageBackendUpdateVolTargetInfo(virStorageSourcePtr target, } if ((len = virFileReadHeaderFD(fd, len, &buf)) < 0) { - virReportSystemError(errno, _("cannot read header '%s'"), target->path); - ret = -1; + if (readflags & VIR_STORAGE_VOL_READ_NOERROR) { + VIR_WARN("ignoring failed header read for '%s'", + target->path); + ret = -2; + } else { + virReportSystemError(errno, + _("cannot read header '%s'"), + target->path); + ret = -1; + } goto cleanup; } @@ -1663,7 +1682,7 @@ virStorageBackendUpdateVolTargetInfo(virStorageSourcePtr target, * @vol: Pointer to a volume storage definition * @withBlockVolFormat: true if the caller determined a block file * @openflags: various VolOpenCheckMode flags to handle errors on open - * @readflags: unused + * @readflags: various VolReadErrorMode flags to handle errors on read * * Returns 0 for success, -1 on a legitimate error condition, and -2 * if the openflags used VIR_STORAGE_VOL_OPEN_NOERROR and some sort of diff --git a/src/storage/storage_backend.h b/src/storage/storage_backend.h index 64c46ee..20e6079 100644 --- a/src/storage/storage_backend.h +++ b/src/storage/storage_backend.h @@ -179,6 +179,15 @@ enum { VIR_STORAGE_VOL_OPEN_DIR = 1 << 4, /* directories okay */ }; +/* VolReadErrorMode flags + * If flag is present, then operation won't cause fatal error for + * specified operation, rather a VIR_WARN will be issued and a -2 returned + * for function call + */ +enum { + VIR_STORAGE_VOL_READ_NOERROR = 1 << 0, /* ignore *read errors */ +}; + # define VIR_STORAGE_VOL_OPEN_DEFAULT (VIR_STORAGE_VOL_OPEN_REG |\ VIR_STORAGE_VOL_OPEN_BLOCK) -- 2.5.0 -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list