From f6a9bc336b600e1266e6eebb0972d75d5b93aea9 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Fri, 5 Mar 2021 17:36:04 -0500 Subject: cifs: allocate buffer in the caller of build_path_from_dentry() build_path_from_dentry() open-codes dentry_path_raw(). The reason we can't use dentry_path_raw() in there (and postprocess the result as needed) is that the callers of build_path_from_dentry() expect that the object to be freed on cleanup and the string to be used are at the same address. That's painful, since the path is naturally built end-to-beginning - we start at the leaf and go through the ancestors, accumulating the pathname. Life would be easier if we left the buffer allocation to callers. It wouldn't be exact-sized buffer, but none of the callers keep the result for long - it's always freed before the caller returns. So there's no need to do exact-sized allocation; better use __getname()/__putname(), same as we do for pathname arguments of syscalls. What's more, there's no need to do allocation under spinlocks, so GFP_ATOMIC is not needed. Next patch will replace the open-coded dentry_path_raw() (in build_path_from_dentry_optional_prefix()) with calling the real thing. This patch only introduces wrappers for allocating/freeing the buffers and switches to new calling conventions: build_path_from_dentry(dentry, buf) expects buf to be address of a page-sized object or NULL, return value is a pathname built inside that buffer on success, ERR_PTR(-ENOMEM) if buf is NULL and ERR_PTR(-ENAMETOOLONG) if the pathname won't fit into page. Note that we don't need to check for failure when allocating the buffer in the caller - build_path_from_dentry() will do the right thing. Signed-off-by: Al Viro Signed-off-by: Steve French --- fs/cifs/cifs_dfs_ref.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'fs/cifs/cifs_dfs_ref.c') diff --git a/fs/cifs/cifs_dfs_ref.c b/fs/cifs/cifs_dfs_ref.c index ecee2864972d..c87c37cf2914 100644 --- a/fs/cifs/cifs_dfs_ref.c +++ b/fs/cifs/cifs_dfs_ref.c @@ -302,6 +302,7 @@ static struct vfsmount *cifs_dfs_do_automount(struct dentry *mntpt) struct cifs_sb_info *cifs_sb; struct cifs_ses *ses; struct cifs_tcon *tcon; + void *page; char *full_path, *root_path; unsigned int xid; int rc; @@ -324,10 +325,13 @@ static struct vfsmount *cifs_dfs_do_automount(struct dentry *mntpt) goto cdda_exit; } + page = alloc_dentry_path(); /* always use tree name prefix */ - full_path = build_path_from_dentry_optional_prefix(mntpt, true); - if (full_path == NULL) - goto cdda_exit; + full_path = build_path_from_dentry_optional_prefix(mntpt, page, true); + if (IS_ERR(full_path)) { + mnt = ERR_CAST(full_path); + goto free_full_path; + } convert_delimiter(full_path, '\\'); @@ -385,7 +389,7 @@ static struct vfsmount *cifs_dfs_do_automount(struct dentry *mntpt) free_root_path: kfree(root_path); free_full_path: - kfree(full_path); + free_dentry_path(page); cdda_exit: cifs_dbg(FYI, "leaving %s\n" , __func__); return mnt; -- cgit