From b5ce1d83a62fc109d8e815b1fc71dcdb0d26bc49 Mon Sep 17 00:00:00 2001 From: Yoshihisa Abe Date: Mon, 25 Oct 2010 02:03:44 -0400 Subject: 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 Signed-off-by: Jan Harkes Signed-off-by: Linus Torvalds --- fs/coda/cnode.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) (limited to 'fs/coda/cnode.c') 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 */ -- cgit v1.2.3-58-ga151