On 04/02/2014 12:36 PM, Eric Blake wrote:
> 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/*/&/
>
Doh, sorry bout that. Fixed.
>> } 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.
>
Agreed, I was just preserving the original behavior. Fixed to unconditionally
raise error and return -1.
>
>> /* 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].
>
Fixed.
>> - 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].
>
Fixed with ignore_value() and pushed now. Thanks Eric!
- Cole
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