[PATCH 14/15] VFS: Combine inode checks with d_is_negative() and d_is_positive() in pathwalk

From: David Howells
Date: Wed Mar 25 2015 - 10:46:15 EST


Where we have:

if (!dentry->d_inode || d_is_negative(dentry)) {

type constructions in pathwalk we should be able to eliminate the check of
d_inode and rely solely on the result of d_is_negative() or d_is_positive().

What we do have to take care to do is to read d_inode after calling a
d_is_xxx() typecheck function to get the barriering right.

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---

fs/namei.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index c83145af4bfc..66234b836360 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1586,7 +1586,7 @@ static inline int walk_component(struct nameidata *nd, struct path *path,
inode = path->dentry->d_inode;
}
err = -ENOENT;
- if (!inode || d_is_negative(path->dentry))
+ if (d_is_negative(path->dentry))
goto out_path_put;

if (should_follow_link(path->dentry, follow)) {
@@ -2313,7 +2313,7 @@ mountpoint_last(struct nameidata *nd, struct path *path)
mutex_unlock(&dir->d_inode->i_mutex);

done:
- if (!dentry->d_inode || d_is_negative(dentry)) {
+ if (d_is_negative(dentry)) {
error = -ENOENT;
dput(dentry);
goto out;
@@ -3040,7 +3040,7 @@ retry_lookup:
finish_lookup:
/* we _can_ be in RCU mode here */
error = -ENOENT;
- if (!inode || d_is_negative(path->dentry)) {
+ if (d_is_negative(path->dentry)) {
path_to_nameidata(path, nd);
goto out;
}

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