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/xattr.c | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-) (limited to 'fs/cifs/xattr.c') diff --git a/fs/cifs/xattr.c b/fs/cifs/xattr.c index 0195a9be3d28..e351b945135b 100644 --- a/fs/cifs/xattr.c +++ b/fs/cifs/xattr.c @@ -113,6 +113,7 @@ static int cifs_xattr_set(const struct xattr_handler *handler, struct tcon_link *tlink; struct cifs_tcon *pTcon; const char *full_path; + void *page; tlink = cifs_sb_tlink(cifs_sb); if (IS_ERR(tlink)) @@ -120,10 +121,11 @@ static int cifs_xattr_set(const struct xattr_handler *handler, pTcon = tlink_tcon(tlink); xid = get_xid(); + page = alloc_dentry_path(); - full_path = build_path_from_dentry(dentry); - if (full_path == NULL) { - rc = -ENOMEM; + full_path = build_path_from_dentry(dentry, page); + if (IS_ERR(full_path)) { + rc = PTR_ERR(full_path); goto out; } /* return dos attributes as pseudo xattr */ @@ -235,7 +237,7 @@ static int cifs_xattr_set(const struct xattr_handler *handler, } out: - kfree(full_path); + free_dentry_path(page); free_xid(xid); cifs_put_tlink(tlink); return rc; @@ -298,6 +300,7 @@ static int cifs_xattr_get(const struct xattr_handler *handler, struct tcon_link *tlink; struct cifs_tcon *pTcon; const char *full_path; + void *page; tlink = cifs_sb_tlink(cifs_sb); if (IS_ERR(tlink)) @@ -305,10 +308,11 @@ static int cifs_xattr_get(const struct xattr_handler *handler, pTcon = tlink_tcon(tlink); xid = get_xid(); + page = alloc_dentry_path(); - full_path = build_path_from_dentry(dentry); - if (full_path == NULL) { - rc = -ENOMEM; + full_path = build_path_from_dentry(dentry, page); + if (IS_ERR(full_path)) { + rc = PTR_ERR(full_path); goto out; } @@ -401,7 +405,7 @@ static int cifs_xattr_get(const struct xattr_handler *handler, rc = -EOPNOTSUPP; out: - kfree(full_path); + free_dentry_path(page); free_xid(xid); cifs_put_tlink(tlink); return rc; @@ -415,6 +419,7 @@ ssize_t cifs_listxattr(struct dentry *direntry, char *data, size_t buf_size) struct tcon_link *tlink; struct cifs_tcon *pTcon; const char *full_path; + void *page; if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_XATTR) return -EOPNOTSUPP; @@ -425,10 +430,11 @@ ssize_t cifs_listxattr(struct dentry *direntry, char *data, size_t buf_size) pTcon = tlink_tcon(tlink); xid = get_xid(); + page = alloc_dentry_path(); - full_path = build_path_from_dentry(direntry); - if (full_path == NULL) { - rc = -ENOMEM; + full_path = build_path_from_dentry(direntry, page); + if (IS_ERR(full_path)) { + rc = PTR_ERR(full_path); goto list_ea_exit; } /* return dos attributes as pseudo xattr */ @@ -442,7 +448,7 @@ ssize_t cifs_listxattr(struct dentry *direntry, char *data, size_t buf_size) rc = pTcon->ses->server->ops->query_all_EAs(xid, pTcon, full_path, NULL, data, buf_size, cifs_sb); list_ea_exit: - kfree(full_path); + free_dentry_path(page); free_xid(xid); cifs_put_tlink(tlink); return rc; -- cgit v1.2.3