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>
diff --git a/fs/coda/file.c b/fs/coda/file.c
index ad3cd2a..c4e3957 100644
--- a/fs/coda/file.c
+++ b/fs/coda/file.c
@@ -16,6 +16,7 @@
#include <linux/cred.h>
#include <linux/errno.h>
#include <linux/smp_lock.h>
+#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <asm/uaccess.h>
@@ -109,19 +110,24 @@
coda_inode = coda_file->f_path.dentry->d_inode;
host_inode = host_file->f_path.dentry->d_inode;
+
+ cii = ITOC(coda_inode);
+ spin_lock(&cii->c_lock);
coda_file->f_mapping = host_file->f_mapping;
if (coda_inode->i_mapping == &coda_inode->i_data)
coda_inode->i_mapping = host_inode->i_mapping;
/* only allow additional mmaps as long as userspace isn't changing
* the container file on us! */
- else if (coda_inode->i_mapping != host_inode->i_mapping)
+ else if (coda_inode->i_mapping != host_inode->i_mapping) {
+ spin_unlock(&cii->c_lock);
return -EBUSY;
+ }
/* keep track of how often the coda_inode/host_file has been mmapped */
- cii = ITOC(coda_inode);
cii->c_mapcount++;
cfi->cfi_mapcount++;
+ spin_unlock(&cii->c_lock);
return host_file->f_op->mmap(host_file, vma);
}
@@ -185,11 +191,13 @@
cii = ITOC(coda_inode);
/* did we mmap this file? */
+ spin_lock(&cii->c_lock);
if (coda_inode->i_mapping == &host_inode->i_data) {
cii->c_mapcount -= cfi->cfi_mapcount;
if (!cii->c_mapcount)
coda_inode->i_mapping = &coda_inode->i_data;
}
+ spin_unlock(&cii->c_lock);
fput(cfi->cfi_container);
kfree(coda_file->private_data);