[PATCH 1/3] NFS: Optimise away the close-to-open GETATTR when we have NFSv4 OPEN

[PATCH 1/3] NFS: Optimise away the close-to-open GETATTR when we have NFSv4 OPEN

[Trond Myklebust]

NFSv4 should not need to perform an extra close-to-open GETATTR as part
of the process of looking up a regular file, since the OPEN call will
do that for us.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
 fs/nfs/dir.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 73f8b43d988c..4a73bd8b4517 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1012,13 +1012,25 @@ int nfs_lookup_verify_inode(struct inode *inode, unsigned int flags)
 
 	if (IS_AUTOMOUNT(inode))
 		return 0;
+
+	if (flags & LOOKUP_OPEN) {
+		switch (inode->i_mode & S_IFMT) {
+		case S_IFREG:
+			/* A NFSv4 OPEN will revalidate later */
+			if (server->caps & NFS_CAP_ATOMIC_OPEN)
+				goto out;
+			/* Fallthrough */
+		case S_IFDIR:
+			if (server->flags & NFS_MOUNT_NOCTO)
+				break;
+			/* NFS close-to-open cache consistency validation */
+			goto out_force;
+		}
+	}
+
 	/* VFS wants an on-the-wire revalidation */
 	if (flags & LOOKUP_REVAL)
 		goto out_force;
-	/* This is an open(2) */
-	if ((flags & LOOKUP_OPEN) && !(server->flags & NFS_MOUNT_NOCTO) &&
-	    (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)))
-		goto out_force;
 out:
 	return (inode->i_nlink == 0) ? -ENOENT : 0;
 out_force:
-- 
2.17.0

[PATCH 2/3] NFS: If the VFS sets LOOKUP_REVAL then force a lookup of the dentry

[Trond Myklebust]

If nfs_lookup_revalidate() is called with LOOKUP_REVAL because a
previous path lookup failed, then we ought to force a full lookup
of the component name.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
 fs/nfs/dir.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 4a73bd8b4517..9dde88334c9c 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1118,7 +1118,7 @@ static int nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
 		goto out_set_verifier;
 
 	/* Force a full look up iff the parent directory has changed */
-	if (!nfs_is_exclusive_create(dir, flags) &&
+	if (!(flags & (LOOKUP_EXCL | LOOKUP_REVAL)) &&
 	    nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU)) {
 		error = nfs_lookup_verify_inode(inode, flags);
 		if (error) {
-- 
2.17.0

[PATCH 3/3] NFS: Optimise away lookups for rename targets

[Trond Myklebust]

We can optimise away any lookup for a rename target, unless we're
being asked to revalidate a dentry that might be in use.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
 fs/nfs/dir.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 9dde88334c9c..b315f53b3aec 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1051,13 +1051,15 @@ int nfs_lookup_verify_inode(struct inode *inode, unsigned int flags)
  *
  * If LOOKUP_RCU prevents us from performing a full check, return 1
  * suggesting a reval is needed.
+ *
+ * Note that when creating a new file, or looking up a rename target,
+ * then it shouldn't be necessary to revalidate a negative dentry.
  */
 static inline
 int nfs_neg_need_reval(struct inode *dir, struct dentry *dentry,
 		       unsigned int flags)
 {
-	/* Don't revalidate a negative dentry if we're creating a new file */
-	if (flags & LOOKUP_CREATE)
+	if (flags & (LOOKUP_CREATE | LOOKUP_RENAME_TARGET))
 		return 0;
 	if (NFS_SERVER(dir)->flags & NFS_MOUNT_LOOKUP_CACHE_NONEG)
 		return 1;
@@ -1347,7 +1349,7 @@ struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, unsigned in
 	 * If we're doing an exclusive create, optimize away the lookup
 	 * but don't hash the dentry.
 	 */
-	if (nfs_is_exclusive_create(dir, flags))
+	if (nfs_is_exclusive_create(dir, flags) || flags & LOOKUP_RENAME_TARGET)
 		return NULL;
 
 	res = ERR_PTR(-ENOMEM);
-- 
2.17.0