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swapon: rewrite SWSUSPEND signature rather than exec mkswap 

> On Thu, Jan 22, 2009 at 04:46:57PM +0000, Hugh Dickins wrote:
> Though your swapon may mkswap for suspend reasons: hmm, wouldn't it
> do very much better just to rewrite the swap signature, than exec
> mkswap - maybe nobody ever uses the badpages list, but it really
> should be respected.

CC: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Karel Zak <kzak@redhat.com>
This commit is contained in:
Karel Zak 2009-03-02 16:41:03 +01:00
parent 05c79b7838
commit 617d8a3bf4
1 changed files with 33 additions and 11 deletions
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44
mount/swapon.c
View File

@ -48,6 +48,9 @@ enum {
SIG_SWSUSPEND
};
#define SWAP_SIGNATURE "SWAPSPACE2"
#define SWAP_SIGNATURE_SZ (sizeof(SWAP_SIGNATURE) - 1)
int all;
int priority = -1; /* non-prioritized swap by default */
@ -228,6 +231,30 @@ swap_reinitialize(const char *device) {
return -1; /* error */
}
static int
swap_rewrite_signature(const char *devname, unsigned int pagesize)
{
int fd, rc = -1;
fd = open(devname, O_WRONLY);
if (fd == -1) {
warn(_("%s: open failed"), devname);
return -1;
}
if (lseek(fd, pagesize - SWAP_SIGNATURE_SZ, SEEK_SET) < 0)
goto err;
if (write(fd, (void *) SWAP_SIGNATURE,
SWAP_SIGNATURE_SZ) != SWAP_SIGNATURE_SZ)
goto err;
rc = 0;
err:
close(fd);
return rc;
}
static int
swap_detect_signature(const char *buf, int *sig)
{
@ -271,9 +298,9 @@ swap_get_header(int fd, int *sig, unsigned int *pagesize)
continue;
/* the smallest swap area is PAGE_SIZE*10, it means
* 40k, that's less than MAX_PAGESIZE */
if (datasz < (page - 10))
if (datasz < (page - SWAP_SIGNATURE_SZ))
break;
if (swap_detect_signature(buf + page - 10, sig)) {
if (swap_detect_signature(buf + page - SWAP_SIGNATURE_SZ, sig)) {
*pagesize = page;
break;
}
@ -318,7 +345,6 @@ swap_get_size(const char *hdr, const char *devname, unsigned int pagesize)
static int
swapon_checks(const char *special)
{
int reinitialize = 0;
struct stat st;
int fd = -1, sig;
char *hdr = NULL;
@ -384,7 +410,8 @@ swapon_checks(const char *special)
warn(_("%s: swap format pagesize does not match."
" Reinitializing the swap."),
special);
reinitialize = 1;
if (swap_reinitialize(special) < 0)
goto err;
}
} else if (sig == SIG_SWSUSPEND) {
/* We have to reinitialize swap with old (=useless) software suspend
@ -392,20 +419,15 @@ swapon_checks(const char *special)
* corruption the next time an attempt at unsuspending is made.
*/
warnx(_("%s: software suspend data detected. "
"Reinitializing the swap."),
"Rewriting the swap signature."),
special);
reinitialize = 1;
}
if (reinitialize) {
if (swap_reinitialize(special) < 0)
if (swap_rewrite_signature(special, pagesize) < 0)
goto err;
}
free(hdr);
close(fd);
return 0;
err:
if (fd != -1)
close(fd);