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storage: Handle readflags errors

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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.
This commit is contained in:
John Ferlan 2015-11-24 11:15:53 -05:00
parent 1edfce9b18
commit 1bc84b0a08
2 changed files with 40 additions and 12 deletions
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43
src/storage/storage_backend.c
View File

@ -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

9
src/storage/storage_backend.h
View File

@ -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)