From fb2d5b86aff355a27ebfc132d3c99f4a940cc3fe Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Fri, 7 Jan 2011 17:49:26 +1100 Subject: fs: name case update method smpfs and ncpfs want to update a live dentry name in-place. Rather than have them open code the locking, provide a documented dcache API. Signed-off-by: Nick Piggin --- drivers/staging/smbfs/cache.c | 4 ++-- fs/dcache.c | 27 +++++++++++++++++++++++++++ fs/ncpfs/dir.c | 35 ++++++----------------------------- include/linux/dcache.h | 2 ++ 4 files changed, 37 insertions(+), 31 deletions(-) diff --git a/drivers/staging/smbfs/cache.c b/drivers/staging/smbfs/cache.c index dbb98658148..dbd2e1df3ba 100644 --- a/drivers/staging/smbfs/cache.c +++ b/drivers/staging/smbfs/cache.c @@ -145,8 +145,8 @@ smb_fill_cache(struct file *filp, void *dirent, filldir_t filldir, goto end_advance; } else { hashed = 1; - memcpy((char *) newdent->d_name.name, qname->name, - newdent->d_name.len); + /* dir i_mutex is locked because we're in readdir */ + dentry_update_name_case(newdent, qname); } if (!newdent->d_inode) { diff --git a/fs/dcache.c b/fs/dcache.c index 6ee6bc40cb6..814e5f491e9 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1589,6 +1589,33 @@ void d_rehash(struct dentry * entry) } EXPORT_SYMBOL(d_rehash); +/** + * dentry_update_name_case - update case insensitive dentry with a new name + * @dentry: dentry to be updated + * @name: new name + * + * Update a case insensitive dentry with new case of name. + * + * dentry must have been returned by d_lookup with name @name. Old and new + * name lengths must match (ie. no d_compare which allows mismatched name + * lengths). + * + * Parent inode i_mutex must be held over d_lookup and into this call (to + * keep renames and concurrent inserts, and readdir(2) away). + */ +void dentry_update_name_case(struct dentry *dentry, struct qstr *name) +{ + BUG_ON(!mutex_is_locked(&dentry->d_inode->i_mutex)); + BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */ + + spin_lock(&dcache_lock); + spin_lock(&dentry->d_lock); + memcpy((unsigned char *)dentry->d_name.name, name->name, name->len); + spin_unlock(&dentry->d_lock); + spin_unlock(&dcache_lock); +} +EXPORT_SYMBOL(dentry_update_name_case); + /* * When switching names, the actual string doesn't strictly have to * be preserved in the target - because we're dropping the target diff --git a/fs/ncpfs/dir.c b/fs/ncpfs/dir.c index d6e6453881c..e80ea4e37c4 100644 --- a/fs/ncpfs/dir.c +++ b/fs/ncpfs/dir.c @@ -611,35 +611,12 @@ ncp_fill_cache(struct file *filp, void *dirent, filldir_t filldir, shrink_dcache_parent(newdent); /* - * It is not as dangerous as it looks. NetWare's OS2 namespace is - * case preserving yet case insensitive. So we update dentry's name - * as received from server. We found dentry via d_lookup with our - * hash, so we know that hash does not change, and so replacing name - * should be reasonably safe. + * NetWare's OS2 namespace is case preserving yet case + * insensitive. So we update dentry's name as received from + * server. Parent dir's i_mutex is locked because we're in + * readdir. */ - if (qname.len == newdent->d_name.len && - memcmp(newdent->d_name.name, qname.name, newdent->d_name.len)) { - struct inode *inode = newdent->d_inode; - - /* - * Inside ncpfs all uses of d_name are either for debugging, - * or on functions which acquire inode mutex (mknod, creat, - * lookup). So grab i_mutex here, to be sure. d_path - * uses dcache_lock when generating path, so we should too. - * And finally d_compare is protected by dentry's d_lock, so - * here we go. - */ - if (inode) - mutex_lock(&inode->i_mutex); - spin_lock(&dcache_lock); - spin_lock(&newdent->d_lock); - memcpy((char *) newdent->d_name.name, qname.name, - newdent->d_name.len); - spin_unlock(&newdent->d_lock); - spin_unlock(&dcache_lock); - if (inode) - mutex_unlock(&inode->i_mutex); - } + dentry_update_name_case(newdent, &qname); } if (!newdent->d_inode) { @@ -657,7 +634,7 @@ ncp_fill_cache(struct file *filp, void *dirent, filldir_t filldir, } else { struct inode *inode = newdent->d_inode; - mutex_lock(&inode->i_mutex); + mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD); ncp_update_inode2(inode, entry); mutex_unlock(&inode->i_mutex); } diff --git a/include/linux/dcache.h b/include/linux/dcache.h index cbfc9567e4e..6cdf4995c90 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -290,6 +290,8 @@ static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *in return res; } +extern void dentry_update_name_case(struct dentry *, struct qstr *); + /* used for rename() and baskets */ extern void d_move(struct dentry *, struct dentry *); extern struct dentry *d_ancestor(struct dentry *, struct dentry *); -- cgit v1.2.3