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Factor out is_bare test. 

Instead of open coding (and using horrible gotos), make this
a separate function.

Also fix the check for end of device - SEEK_END doesn't work on
block devices.

Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
NeilBrown 2010-11-22 20:58:06 +11:00
parent 403410eb97
commit 52e965c296
1 changed files with 29 additions and 19 deletions
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48
Incremental.c
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@ -1030,6 +1030,34 @@ static int partition_try_spare(char *devname, int *dfdp, struct dev_policy *pol,
return 0;
}
static int is_bare(int dfd)
{
unsigned long long size = 0;
char bufpad[4096 + 4096];
char *buf = (char*)(((long)bufpad + 4096) & ~4095);
if (lseek(dfd, 0, SEEK_SET) != 0 ||
read(dfd, buf, 4096) != 4096)
return 0;
if (buf[0] != '\0' && buf[0] != '\x5a' && buf[0] != '\xff')
return 0;
if (memcmp(buf, buf+1, 4095) != 0)
return 0;
/* OK, first 4K appear blank, try the end. */
get_dev_size(dfd, NULL, &size);
if (lseek(dfd, size-4096, SEEK_SET) < 0 ||
read(dfd, buf, 4096) != 4096)
return 0;
if (buf[0] != '\0' && buf[0] != '\x5a' && buf[0] != '\xff')
return 0;
if (memcmp(buf, buf+1, 4095) != 0)
return 0;
return 1;
}
/* adding a spare to a regular array is quite different from adding one to
* a set-of-partitions virtual array.
@ -1043,8 +1071,6 @@ static int try_spare(char *devname, int *dfdp, struct dev_policy *pol,
int rv;
int arrays_ok = 0;
int partitions_ok = 0;
char bufpad[4096 + 4096];
char *buf = (char*)(((long)bufpad + 4096) & ~4095);
int dfd = *dfdp;
/* Can only add a spare if device has at least one domains */
@ -1058,28 +1084,12 @@ static int try_spare(char *devname, int *dfdp, struct dev_policy *pol,
* yet even if action=-spare
*/
if (lseek(dfd, 0, SEEK_SET) != 0 ||
read(dfd, buf, 4096) != 4096) {
not_bare:
if (!is_bare(dfd)) {
if (verbose > 1)
fprintf(stderr, Name ": %s is not bare, so not considering as a spare\n",
devname);
return 1;
}
if (buf[0] != '\0' && buf[0] != '\x5a' && buf[0] != '\xff')
goto not_bare;
if (memcmp(buf, buf+1, 4095) != 0)
goto not_bare;
/* OK, first 4K appear blank, try the end. */
if (lseek(dfd, -4096, SEEK_END) < 0 ||
read(dfd, buf, 4096) != 4096)
goto not_bare;
if (buf[0] != '\0' && buf[0] != '\x5a' && buf[0] != '\xff')
goto not_bare;
if (memcmp(buf, buf+1, 4095) != 0)
goto not_bare;
/* This device passes our test for 'is bare'.
* Let's see what policy allows for such things.