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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/file.c
parent3a99c6319064af3f2e18eb929f638d555dbf7a62 (diff)
downloadlinux-linaro-b5ce1d83a62fc109d8e815b1fc71dcdb0d26bc49.tar.gz
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/file.c')
-rw-r--r--fs/coda/file.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/fs/coda/file.c b/fs/coda/file.c
index ad3cd2abeeb..c4e395781d4 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_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
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 @@ int coda_release(struct inode *coda_inode, struct file *coda_file)
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);