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authorLee Schermerhorn <Lee.Schermerhorn@hp.com>2008-04-28 02:12:36 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-28 08:58:20 -0700
commita43361cf3cb6fb6431fdbfb0f3ef26a334826160 (patch)
tree8ec343f73bb61c1ef08a32c78e912a7506c932bf
parent3e1f064562fcff7bf3856bc1d00dfa84d4f121cc (diff)
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mempolicy: fix parsing of tmpfs mpol mount option
Parsing of new mode flags in the tmpfs mpol mount option is slightly broken: Setting a valid flag works OK: #mount -o remount,mpol=bind=static:1-2 /dev/shm #mount ... tmpfs on /dev/shm type tmpfs (rw,mpol=bind=static:1-2) ... However, we can't remove them or change them, once we've set a valid flag: #mount -o remount,mpol=bind:1-2 /dev/shm #mount ... tmpfs on /dev/shm type tmpfs (rw,mpol=bind:1-2) ... It SAYS it removed it, but that's just a copy of the input string. If we now try to set it to a different flag, we get: #mount -o remount,mpol=bind=relative:1-2 /dev/shm mount: /dev/shm not mounted already, or bad option And on the console, we see: tmpfs: Bad value 'bind' for mount option 'mpol' ^ lost remainder of string Furthermore, bogus flags are accepted with out error. Granted, they are a no-op: #mount -o remount,mpol=interleave=foo:0-3 /dev/shm #mount ... tmpfs on /dev/shm type tmpfs (rw,mpol=interleave=foo:0-3) Again, that's just a copy of the input string shown by the mount command. This patch fixes the behavior by pre-zeroing the flags so that only one of the mutually exclusive flags can be set at one time. It also reports an error when an unrecognized flag is specified. The check for both flags being set is removed because it can't happen with this implementation. If we ever want to support multiple non-exclusive flags, this area will need rework and we will need to check that any mutually exclusive flags aren't specified. Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: David Rientjes <rientjes@google.com> Cc: Paul Jackson <pj@sgi.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: Andi Kleen <ak@suse.de> Cc: Eric Whitney <eric.whitney@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/shmem.c16
1 files changed, 11 insertions, 5 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index 9435f298dd7..177c7a7d2bb 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1125,20 +1125,26 @@ static int shmem_parse_mpol(char *value, unsigned short *policy,
*policy_nodes = node_states[N_HIGH_MEMORY];
err = 0;
}
+
+ *mode_flags = 0;
if (flags) {
+ /*
+ * Currently, we only support two mutually exclusive
+ * mode flags.
+ */
if (!strcmp(flags, "static"))
*mode_flags |= MPOL_F_STATIC_NODES;
- if (!strcmp(flags, "relative"))
+ else if (!strcmp(flags, "relative"))
*mode_flags |= MPOL_F_RELATIVE_NODES;
-
- if ((*mode_flags & MPOL_F_STATIC_NODES) &&
- (*mode_flags & MPOL_F_RELATIVE_NODES))
- err = 1;
+ else
+ err = 1; /* unrecognized flag */
}
out:
/* Restore string for error message */
if (nodelist)
*--nodelist = ':';
+ if (flags)
+ *--flags = '=';
return err;
}