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fs: name case update method

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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 <npiggin@kernel.dk>
This commit is contained in:
Nick Piggin
2011-01-07 17:49:26 +11:00
parent 2bc334dcc7
commit fb2d5b86af
4 changed files with 37 additions and 31 deletions
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35
fs/ncpfs/dir.c
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@@ -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);
}