On 04/02/2014 09:54 AM, Cole Robinson wrote:
Currently VolOpen notifies the user of a potentially non-fatal failure by returning -2 and logging a VIR_WARN or VIR_INFO. Unfortunately most callers treat -2 as fatal but don't actually report any message with the error APIs.
Rename the VOL_OPEN_ERROR flag to VOL_OPEN_NOERROR. If NOERROR is specified, we preserve the current behavior of returning -2 (there's only one caller that wants this).
However in the default case, only return -1, and actually use the error APIs. Fix up a couple callers as a result. --- src/storage/storage_backend.c | 77 ++++++++++++++++++++++++-------------- src/storage/storage_backend.h | 7 ++-- src/storage/storage_backend_fs.c | 28 +++++--------- src/storage/storage_backend_scsi.c | 3 -- 4 files changed, 62 insertions(+), 53 deletions(-)
+ * Returns -1 on error. If VIR_STORAGE_VOL_OPEN_NOERROR is passed, we + * return -2 if file mode is unexpected or the volume is a dangling + * symbolic link.
Seems fair; let's see how it works below...
*/ int virStorageBackendVolOpen(const char *path, struct stat *sb, @@ -1288,9 +1289,10 @@ virStorageBackendVolOpen(const char *path, struct stat *sb, { int fd, mode = 0; char *base = last_component(path); + bool noerror = (flags * VIR_STORAGE_VOL_OPEN_NOERROR);
Whoops[1] - that returns true for any non-zero flags value. I think you meant s/*/&/
} else { - VIR_WARN("ignoring unexpected type for file '%s'", path); VIR_FORCE_CLOSE(fd); - return -2; + if (noerror) { + VIR_WARN("ignoring unexpected type for file '%s'", path); + return -2; + } + virReportError(VIR_ERR_INTERNAL_ERROR, + _("unexpected type for file '%s'"), path); + return -1;
...so far, so good (all cases of 'return -2' are guarded by noerror, and an error is issued before returning -1).
}
if (virSetBlocking(fd, true) < 0) { + VIR_FORCE_CLOSE(fd); + if (noerror) { + VIR_WARN("unable to set blocking mode for '%s'", path); + return -2; + }
But this one feels wrong[2]. If we get here, we KNOW the fd has the expected type, and we successfully opened it. This is a case where the system is hosed, and we should loudly and unconditionally fail with -1, rather than returning -2 on noerror.
/* VolOpenCheckMode flags */ enum { - VIR_STORAGE_VOL_OPEN_ERROR = 1 << 0, /* warn if unexpected type - * encountered */ + VIR_STORAGE_VOL_OPEN_NOERROR = 1 << 0, /* don't error if unexpected type + * encountered, just warn */ VIR_STORAGE_VOL_OPEN_REG = 1 << 1, /* regular files okay */ VIR_STORAGE_VOL_OPEN_BLOCK = 1 << 2, /* block files okay */ VIR_STORAGE_VOL_OPEN_CHAR = 1 << 3, /* char files okay */ VIR_STORAGE_VOL_OPEN_DIR = 1 << 4, /* directories okay */
Cosmetic, but alignment of = is now off [3].
- if (virStorageBackendUpdateVolTargetInfo(&vol->backingStore, - false, - VIR_STORAGE_VOL_OPEN_DEFAULT) < 0) { - /* The backing file is currently unavailable, the capacity, - * allocation, owner, group and mode are unknown. Just log the - * error and continue. - * Unfortunately virStorageBackendProbeTarget() might already - * have logged a similar message for the same problem, but only - * if AUTO format detection was used. */ - virReportError(VIR_ERR_INTERNAL_ERROR, - _("cannot probe backing volume info: %s"), - vol->backingStore.path); - } + virStorageBackendUpdateVolTargetInfo(&vol->backingStore, false, + VIR_STORAGE_VOL_OPEN_DEFAULT); + /* If this failed, the backing file is currently unavailable, + * the capacity, allocation, owner, group and mode are unknown. + * An error message was raised, but we just continue. */
You may need an ignore_value() here to keep Coverity quiet about an unchecked error return [4]. This touches code that I'm also working on, so I'm interested in getting it in sooner to avoid rebase churn over repeated iterations. ACK if you fix [1] and [2] above; and up to you whether changes are needed at [3] and [4]. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org