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Coda: add spin lock to protect accesses to struct coda_inode_info.

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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>
This commit is contained in:
Yoshihisa Abe 2010-10-25 02:03:44 -04:00 • committed by Linus Torvalds
parent 3a99c63190
commit b5ce1d83a6
7 changed files with 58 additions and 17 deletions
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17
fs/coda/cache.c
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@ -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;
}