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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/cnode.c
parent3a99c6319064af3f2e18eb929f638d555dbf7a62 (diff)
downloadlinux-b5ce1d83a62fc109d8e815b1fc71dcdb0d26bc49.tar.bz2
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/cnode.c')
-rw-r--r--fs/coda/cnode.c19
1 files changed, 14 insertions, 5 deletions
diff --git a/fs/coda/cnode.c b/fs/coda/cnode.c
index a7a780929eec..602240569c89 100644
--- a/fs/coda/cnode.c
+++ b/fs/coda/cnode.c
@@ -45,13 +45,15 @@ static void coda_fill_inode(struct inode *inode, struct coda_vattr *attr)
static int coda_test_inode(struct inode *inode, void *data)
{
struct CodaFid *fid = (struct CodaFid *)data;
- return coda_fideq(&(ITOC(inode)->c_fid), fid);
+ struct coda_inode_info *cii = ITOC(inode);
+ return coda_fideq(&cii->c_fid, fid);
}
static int coda_set_inode(struct inode *inode, void *data)
{
struct CodaFid *fid = (struct CodaFid *)data;
- ITOC(inode)->c_fid = *fid;
+ struct coda_inode_info *cii = ITOC(inode);
+ cii->c_fid = *fid;
return 0;
}
@@ -71,6 +73,7 @@ struct inode * coda_iget(struct super_block * sb, struct CodaFid * fid,
cii = ITOC(inode);
/* we still need to set i_ino for things like stat(2) */
inode->i_ino = hash;
+ /* inode is locked and unique, no need to grab cii->c_lock */
cii->c_mapcount = 0;
unlock_new_inode(inode);
}
@@ -107,14 +110,20 @@ int coda_cnode_make(struct inode **inode, struct CodaFid *fid, struct super_bloc
}
+/* Although we treat Coda file identifiers as immutable, there is one
+ * special case for files created during a disconnection where they may
+ * not be globally unique. When an identifier collision is detected we
+ * first try to flush the cached inode from the kernel and finally
+ * resort to renaming/rehashing in-place. Userspace remembers both old
+ * and new values of the identifier to handle any in-flight upcalls.
+ * The real solution is to use globally unique UUIDs as identifiers, but
+ * retrofitting the existing userspace code for this is non-trivial. */
void coda_replace_fid(struct inode *inode, struct CodaFid *oldfid,
struct CodaFid *newfid)
{
- struct coda_inode_info *cii;
+ struct coda_inode_info *cii = ITOC(inode);
unsigned long hash = coda_f2i(newfid);
- cii = ITOC(inode);
-
BUG_ON(!coda_fideq(&cii->c_fid, oldfid));
/* replace fid and rehash inode */