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/ioctl.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) (limited to 'fs/cifs/ioctl.c') diff --git a/fs/cifs/ioctl.c b/fs/cifs/ioctl.c index aba573dd86ac..08d99fec593e 100644 --- a/fs/cifs/ioctl.c +++ b/fs/cifs/ioctl.c @@ -43,12 +43,15 @@ static long cifs_ioctl_query_info(unsigned int xid, struct file *filep, struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb); struct dentry *dentry = filep->f_path.dentry; const unsigned char *path; + void *page = alloc_dentry_path(); __le16 *utf16_path = NULL, root_path; int rc = 0; - path = build_path_from_dentry(dentry); - if (path == NULL) - return -ENOMEM; + path = build_path_from_dentry(dentry, page); + if (IS_ERR(path)) { + free_dentry_path(page); + return PTR_ERR(path); + } cifs_dbg(FYI, "%s %s\n", __func__, path); @@ -73,7 +76,7 @@ static long cifs_ioctl_query_info(unsigned int xid, struct file *filep, ici_exit: if (utf16_path != &root_path) kfree(utf16_path); - kfree(path); + free_dentry_path(page); return rc; } -- cgit v1.2.3-59-g8ed1b