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authorAl Viro <viro@zeniv.linux.org.uk>2021-03-06 01:36:04 +0300
committerSteve French <stfrench@microsoft.com>2021-04-26 00:28:23 +0300
commitf6a9bc336b600e1266e6eebb0972d75d5b93aea9 (patch)
tree62432d7b429006e2cdab9e9750565eec9e868fd9 /fs/cifs/cifsproto.h
parent8e33cf20ceb7f6d7a7e039f9f82a0cd1f3a6f964 (diff)
downloadlinux-f6a9bc336b600e1266e6eebb0972d75d5b93aea9.tar.xz
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 <viro@zeniv.linux.org.uk> Signed-off-by: Steve French <stfrench@microsoft.com>
Diffstat (limited to 'fs/cifs/cifsproto.h')
-rw-r--r--fs/cifs/cifsproto.h15
1 files changed, 13 insertions, 2 deletions
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index ed6ea0c59cb9..c8faa3e82fe7 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -69,9 +69,20 @@ extern int init_cifs_idmap(void);
extern void exit_cifs_idmap(void);
extern int init_cifs_spnego(void);
extern void exit_cifs_spnego(void);
-extern const char *build_path_from_dentry(struct dentry *);
+extern const char *build_path_from_dentry(struct dentry *, void *);
extern char *build_path_from_dentry_optional_prefix(struct dentry *direntry,
- bool prefix);
+ void *page, bool prefix);
+static inline void *alloc_dentry_path(void)
+{
+ return __getname();
+}
+
+static inline void free_dentry_path(void *page)
+{
+ if (page)
+ __putname(page);
+}
+
extern char *cifs_build_path_to_root(struct smb3_fs_context *ctx,
struct cifs_sb_info *cifs_sb,
struct cifs_tcon *tcon,