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authorAl Viro <viro@zeniv.linux.org.uk>2015-05-04 17:47:11 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2015-05-10 22:20:12 -0400
commit4693a547cded42807ec468947b4d5287f2cb6aa9 (patch)
treecd945ed0efeddbc285f36492a97b459a7bbe32f0 /fs
parent8620c238edbf373aafcc4ee129e76c8e794c5214 (diff)
namei: new calling conventions for walk_component()
instead of a single flag (!= 0 => we want to follow symlinks) pass two bits - WALK_GET (want to follow symlinks) and WALK_PUT (put_link() once we are done looking at the name). The latter matters only for success exits - on failure the caller will discard everything anyway. Suggestions for better variant are welcome; what this thing aims for is making sure that pending put_link() is done *before* walk_component() decides to pick a symlink up, rather than between picking it up and acting upon it. See the next commit for payoff. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs')
-rw-r--r--fs/namei.c30
1 files changed, 20 insertions, 10 deletions
diff --git a/fs/namei.c b/fs/namei.c
index 19e5c8a27ea4..1c9af92518a1 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1577,7 +1577,9 @@ static inline int should_follow_link(struct dentry *dentry, int follow)
return unlikely(d_is_symlink(dentry)) ? follow : 0;
}
-static int walk_component(struct nameidata *nd, int follow)
+enum {WALK_GET = 1, WALK_PUT = 2};
+
+static int walk_component(struct nameidata *nd, int flags)
{
struct path path;
struct inode *inode;
@@ -1587,8 +1589,12 @@ static int walk_component(struct nameidata *nd, int follow)
* to be able to know about the current root directory and
* parent relationships.
*/
- if (unlikely(nd->last_type != LAST_NORM))
- return handle_dots(nd, nd->last_type);
+ if (unlikely(nd->last_type != LAST_NORM)) {
+ err = handle_dots(nd, nd->last_type);
+ if (flags & WALK_PUT)
+ put_link(nd);
+ return err;
+ }
err = lookup_fast(nd, &path, &inode);
if (unlikely(err)) {
if (err < 0)
@@ -1604,7 +1610,9 @@ static int walk_component(struct nameidata *nd, int follow)
goto out_path_put;
}
- if (should_follow_link(path.dentry, follow)) {
+ if (flags & WALK_PUT)
+ put_link(nd);
+ if (should_follow_link(path.dentry, flags & WALK_GET)) {
if (nd->flags & LOOKUP_RCU) {
if (unlikely(nd->path.mnt != path.mnt ||
unlazy_walk(nd, path.dentry))) {
@@ -1816,10 +1824,9 @@ OK:
if (!name)
return 0;
/* last component of nested symlink */
- err = walk_component(nd, LOOKUP_FOLLOW);
- put_link(nd);
+ err = walk_component(nd, WALK_GET | WALK_PUT);
} else {
- err = walk_component(nd, LOOKUP_FOLLOW);
+ err = walk_component(nd, WALK_GET);
}
if (err < 0)
break;
@@ -2017,9 +2024,12 @@ static inline int lookup_last(struct nameidata *nd)
nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
nd->flags &= ~LOOKUP_PARENT;
- err = walk_component(nd, nd->flags & LOOKUP_FOLLOW);
- if (nd->depth)
- put_link(nd);
+ err = walk_component(nd,
+ nd->flags & LOOKUP_FOLLOW
+ ? nd->depth
+ ? WALK_PUT | WALK_GET
+ : WALK_GET
+ : 0);
if (err < 0)
terminate_walk(nd);
return err;