From 617d8a3bf4516924a73a02c5cb7bf4195a7f2c66 Mon Sep 17 00:00:00 2001 From: Karel Zak Date: Mon, 2 Mar 2009 16:41:03 +0100 Subject: [PATCH] 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 Signed-off-by: Karel Zak --- mount/swapon.c | 44 +++++++++++++++++++++++++++++++++----------- 1 file changed, 33 insertions(+), 11 deletions(-) diff --git a/mount/swapon.c b/mount/swapon.c index 1c337c26..d61ff743 100644 --- a/mount/swapon.c +++ b/mount/swapon.c @@ -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); -- 2.39.5