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>
diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index 0b29893..fe3a50a 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -1609,7 +1609,8 @@ int cifs_unlink(struct inode *dir, struct dentry *dentry)
{
int rc = 0;
unsigned int xid;
- const char *full_path = NULL;
+ const char *full_path;
+ void *page;
struct inode *inode = d_inode(dentry);
struct cifsInodeInfo *cifs_inode;
struct super_block *sb = dir->i_sb;
@@ -1629,6 +1630,7 @@ int cifs_unlink(struct inode *dir, struct dentry *dentry)
server = tcon->ses->server;
xid = get_xid();
+ page = alloc_dentry_path();
if (tcon->nodelete) {
rc = -EACCES;
@@ -1637,9 +1639,9 @@ int cifs_unlink(struct inode *dir, struct dentry *dentry)
/* Unlink can be called from rename so we can not take the
* sb->s_vfs_rename_mutex here */
- 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 unlink_out;
}
@@ -1713,7 +1715,7 @@ int cifs_unlink(struct inode *dir, struct dentry *dentry)
cifs_inode = CIFS_I(dir);
CIFS_I(dir)->time = 0; /* force revalidate of dir as well */
unlink_out:
- kfree(full_path);
+ free_dentry_path(page);
kfree(attrs);
free_xid(xid);
cifs_put_tlink(tlink);
@@ -1867,6 +1869,7 @@ int cifs_mkdir(struct user_namespace *mnt_userns, struct inode *inode,
struct cifs_tcon *tcon;
struct TCP_Server_Info *server;
const char *full_path;
+ void *page;
cifs_dbg(FYI, "In cifs_mkdir, mode = %04ho inode = 0x%p\n",
mode, inode);
@@ -1879,9 +1882,10 @@ int cifs_mkdir(struct user_namespace *mnt_userns, struct inode *inode,
xid = get_xid();
- full_path = build_path_from_dentry(direntry);
- if (full_path == NULL) {
- rc = -ENOMEM;
+ page = alloc_dentry_path();
+ full_path = build_path_from_dentry(direntry, page);
+ if (IS_ERR(full_path)) {
+ rc = PTR_ERR(full_path);
goto mkdir_out;
}
@@ -1924,7 +1928,7 @@ int cifs_mkdir(struct user_namespace *mnt_userns, struct inode *inode,
* attributes are invalid now.
*/
CIFS_I(inode)->time = 0;
- kfree(full_path);
+ free_dentry_path(page);
free_xid(xid);
cifs_put_tlink(tlink);
return rc;
@@ -1938,16 +1942,17 @@ int cifs_rmdir(struct inode *inode, struct dentry *direntry)
struct tcon_link *tlink;
struct cifs_tcon *tcon;
struct TCP_Server_Info *server;
- const char *full_path = NULL;
+ const char *full_path;
+ void *page = alloc_dentry_path();
struct cifsInodeInfo *cifsInode;
cifs_dbg(FYI, "cifs_rmdir, inode = 0x%p\n", inode);
xid = get_xid();
- 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 rmdir_exit;
}
@@ -1997,7 +2002,7 @@ int cifs_rmdir(struct inode *inode, struct dentry *direntry)
current_time(inode);
rmdir_exit:
- kfree(full_path);
+ free_dentry_path(page);
free_xid(xid);
return rc;
}
@@ -2072,8 +2077,8 @@ cifs_rename2(struct user_namespace *mnt_userns, struct inode *source_dir,
struct dentry *source_dentry, struct inode *target_dir,
struct dentry *target_dentry, unsigned int flags)
{
- const char *from_name = NULL;
- const char *to_name = NULL;
+ const char *from_name, *to_name;
+ void *page1, *page2;
struct cifs_sb_info *cifs_sb;
struct tcon_link *tlink;
struct cifs_tcon *tcon;
@@ -2091,21 +2096,19 @@ cifs_rename2(struct user_namespace *mnt_userns, struct inode *source_dir,
return PTR_ERR(tlink);
tcon = tlink_tcon(tlink);
+ page1 = alloc_dentry_path();
+ page2 = alloc_dentry_path();
xid = get_xid();
- /*
- * we already have the rename sem so we do not need to
- * grab it again here to protect the path integrity
- */
- from_name = build_path_from_dentry(source_dentry);
- if (from_name == NULL) {
- rc = -ENOMEM;
+ from_name = build_path_from_dentry(source_dentry, page1);
+ if (IS_ERR(from_name)) {
+ rc = PTR_ERR(from_name);
goto cifs_rename_exit;
}
- to_name = build_path_from_dentry(target_dentry);
- if (to_name == NULL) {
- rc = -ENOMEM;
+ to_name = build_path_from_dentry(target_dentry, page2);
+ if (IS_ERR(to_name)) {
+ rc = PTR_ERR(to_name);
goto cifs_rename_exit;
}
@@ -2177,8 +2180,8 @@ cifs_rename2(struct user_namespace *mnt_userns, struct inode *source_dir,
cifs_rename_exit:
kfree(info_buf_source);
- kfree(from_name);
- kfree(to_name);
+ free_dentry_path(page2);
+ free_dentry_path(page1);
free_xid(xid);
cifs_put_tlink(tlink);
return rc;
@@ -2317,7 +2320,8 @@ int cifs_revalidate_dentry_attr(struct dentry *dentry)
int rc = 0;
struct inode *inode = d_inode(dentry);
struct super_block *sb = dentry->d_sb;
- const char *full_path = NULL;
+ const char *full_path;
+ void *page;
int count = 0;
if (inode == NULL)
@@ -2328,11 +2332,10 @@ int cifs_revalidate_dentry_attr(struct dentry *dentry)
xid = get_xid();
- /* can not safely grab the rename sem here if rename calls revalidate
- since that would deadlock */
- full_path = build_path_from_dentry(dentry);
- if (full_path == NULL) {
- rc = -ENOMEM;
+ page = alloc_dentry_path();
+ full_path = build_path_from_dentry(dentry, page);
+ if (IS_ERR(full_path)) {
+ rc = PTR_ERR(full_path);
goto out;
}
@@ -2351,7 +2354,7 @@ int cifs_revalidate_dentry_attr(struct dentry *dentry)
if (rc == -EAGAIN && count++ < 10)
goto again;
out:
- kfree(full_path);
+ free_dentry_path(page);
free_xid(xid);
return rc;
@@ -2613,7 +2616,8 @@ cifs_setattr_unix(struct dentry *direntry, struct iattr *attrs)
{
int rc;
unsigned int xid;
- const char *full_path = NULL;
+ const char *full_path;
+ void *page = alloc_dentry_path();
struct inode *inode = d_inode(direntry);
struct cifsInodeInfo *cifsInode = CIFS_I(inode);
struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
@@ -2634,9 +2638,9 @@ cifs_setattr_unix(struct dentry *direntry, struct iattr *attrs)
if (rc < 0)
goto out;
- 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 out;
}
@@ -2748,7 +2752,7 @@ cifs_setattr_unix(struct dentry *direntry, struct iattr *attrs)
cifsInode->time = 0;
out:
kfree(args);
- kfree(full_path);
+ free_dentry_path(page);
free_xid(xid);
return rc;
}
@@ -2764,7 +2768,8 @@ cifs_setattr_nounix(struct dentry *direntry, struct iattr *attrs)
struct cifsInodeInfo *cifsInode = CIFS_I(inode);
struct cifsFileInfo *wfile;
struct cifs_tcon *tcon;
- const char *full_path = NULL;
+ const char *full_path;
+ void *page = alloc_dentry_path();
int rc = -EACCES;
__u32 dosattr = 0;
__u64 mode = NO_CHANGE_64;
@@ -2778,16 +2783,13 @@ cifs_setattr_nounix(struct dentry *direntry, struct iattr *attrs)
attrs->ia_valid |= ATTR_FORCE;
rc = setattr_prepare(&init_user_ns, direntry, attrs);
- if (rc < 0) {
- free_xid(xid);
- return rc;
- }
+ if (rc < 0)
+ goto cifs_setattr_exit;
- full_path = build_path_from_dentry(direntry);
- if (full_path == NULL) {
- rc = -ENOMEM;
- free_xid(xid);
- return rc;
+ full_path = build_path_from_dentry(direntry, page);
+ if (IS_ERR(full_path)) {
+ rc = PTR_ERR(full_path);
+ goto cifs_setattr_exit;
}
/*
@@ -2937,8 +2939,8 @@ cifs_setattr_nounix(struct dentry *direntry, struct iattr *attrs)
mark_inode_dirty(inode);
cifs_setattr_exit:
- kfree(full_path);
free_xid(xid);
+ free_dentry_path(page);
return rc;
}
