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authorYoshihisa Abe <yoshiabe@cs.cmu.edu>2010-10-25 02:03:44 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2010-10-25 08:02:40 -0700
commitb5ce1d83a62fc109d8e815b1fc71dcdb0d26bc49 (patch)
treeea537c1b6436c36bee3b33d8b4f750124fd7d661 /fs/coda/cache.c
parent3a99c6319064af3f2e18eb929f638d555dbf7a62 (diff)
Coda: add spin lock to protect accesses to struct coda_inode_info.
We mostly need it to protect cached user permissions. The c_flags field is advisory, reading the wrong value is harmless and in the worst case we hit a slow path where we have to make an extra upcall to the userspace cache manager when revalidating a dentry or inode. Signed-off-by: Yoshihisa Abe <yoshiabe@cs.cmu.edu> Signed-off-by: Jan Harkes <jaharkes@cs.cmu.edu> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/coda/cache.c')
-rw-r--r--fs/coda/cache.c17
1 files changed, 12 insertions, 5 deletions
diff --git a/fs/coda/cache.c b/fs/coda/cache.c
index a5bf5771a22a..9060f08e70cf 100644
--- a/fs/coda/cache.c
+++ b/fs/coda/cache.c
@@ -17,6 +17,7 @@
#include <linux/string.h>
#include <linux/list.h>
#include <linux/sched.h>
+#include <linux/spinlock.h>
#include <linux/coda.h>
#include <linux/coda_linux.h>
@@ -31,19 +32,23 @@ void coda_cache_enter(struct inode *inode, int mask)
{
struct coda_inode_info *cii = ITOC(inode);
+ spin_lock(&cii->c_lock);
cii->c_cached_epoch = atomic_read(&permission_epoch);
if (cii->c_uid != current_fsuid()) {
cii->c_uid = current_fsuid();
cii->c_cached_perm = mask;
} else
cii->c_cached_perm |= mask;
+ spin_unlock(&cii->c_lock);
}
/* remove cached acl from an inode */
void coda_cache_clear_inode(struct inode *inode)
{
struct coda_inode_info *cii = ITOC(inode);
+ spin_lock(&cii->c_lock);
cii->c_cached_epoch = atomic_read(&permission_epoch) - 1;
+ spin_unlock(&cii->c_lock);
}
/* remove all acl caches */
@@ -57,13 +62,15 @@ void coda_cache_clear_all(struct super_block *sb)
int coda_cache_check(struct inode *inode, int mask)
{
struct coda_inode_info *cii = ITOC(inode);
- int hit;
+ int hit;
- hit = (mask & cii->c_cached_perm) == mask &&
- cii->c_uid == current_fsuid() &&
- cii->c_cached_epoch == atomic_read(&permission_epoch);
+ spin_lock(&cii->c_lock);
+ hit = (mask & cii->c_cached_perm) == mask &&
+ cii->c_uid == current_fsuid() &&
+ cii->c_cached_epoch == atomic_read(&permission_epoch);
+ spin_unlock(&cii->c_lock);
- return hit;
+ return hit;
}