[PATCH v1 RESEND 00/12] vfs: add the ability to retry on ESTALE to several syscalls

[PATCH v1 RESEND 00/12] vfs: add the ability to retry on ESTALE to several syscalls

[Jeff Layton]

ESTALE errors are a source of pain for many users, primarily those who
are doing work on NFS. When userspace provides a path to a syscall, then
there's really little excuse for returning ESTALE. If userspace gave us
a path that we had to lookup in order to do the call, then it's not
particularly helpful to return ESTALE just because that path went stale
before we could do the actual operation.

We can and should do better here. The kernel should instead catch that
error and retry the lookup and call, while forcing a revalidation of all
dentries involved.

Unfortunately fixing this requires touching the syscalls themselves, or
at least their immediate helper functions. Not all syscalls can be
retried -- only those that take a pathname as an argument.

This set is a first "official" pass at adding ESTALE retry handling to
various syscalls.  With this patchset, I've decided to take the
relatively less controversial approach of just having the kernel retry
once when it gets an ESTALE error. I still think that it's not as strong
as it should be, but it should improve the situation in many common
cases.

I've also tried to engineer this in such a way that if we do decide that
we need to retry more than once, then it should be easy to change that
later. This should cover all of the syscalls in fs/stat.c and
fs/namei.c.

If this approach is reasonable I'll look at adding similar handling to
other path-based vfs calls in a another set. A quick look shows that
we have about 50-odd path-based syscalls that will need similar
handling, so this is just a start.

Comments welcome...

Jeff Layton (12):
  vfs: add a retry_estale helper function to handle retries on ESTALE
  vfs: make fstatat retry on ESTALE errors from getattr call
  vfs: fix readlinkat to retry on ESTALE
  vfs: add new "reval" argument to kern_path_create and
    user_path_create
  vfs: fix mknodat to retry on ESTALE errors
  vfs: fix mkdir to retry on ESTALE errors
  vfs: add a "reval" flag to args for user_path_parent
  vfs: make rmdir retry on ESTALE errors
  vfs: make do_unlinkat retry on ESTALE errors
  vfs: fix symlinkat to retry on ESTALE errors
  vfs: fix linkat to retry on ESTALE errors
  vfs: fix renameat to retry on ESTALE errors

 arch/powerpc/platforms/cell/spufs/syscalls.c |    2 +-
 drivers/base/devtmpfs.c                      |    7 +-
 fs/namei.c                                   |  233 +++++++++++++++-----------
 fs/ocfs2/refcounttree.c                      |    3 +-
 fs/stat.c                                    |   32 +++-
 include/linux/fs.h                           |   21 +++
 include/linux/namei.h                        |    4 +-
 net/unix/af_unix.c                           |    3 +-
 8 files changed, 191 insertions(+), 114 deletions(-)

-- 
1.7.7.6

[PATCH v1 RESEND 01/12] vfs: add a retry_estale helper function to handle retries on ESTALE

[Jeff Layton]

This function is expected to be called from path-based syscalls to help
them decide whether to try the lookup and call again in the event that
they got an -ESTALE return back on an earier try.

Currently, we only retry the call once on an ESTALE error, but in the
event that we decide that that's not enough in the future, we should be
able to change the logic in this helper without too much effort.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 include/linux/fs.h |   21 +++++++++++++++++++++
 1 files changed, 21 insertions(+), 0 deletions(-)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 8de6755..3c0bcda 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2026,6 +2026,27 @@ extern struct file * dentry_open(struct dentry *, struct vfsmount *, int,
 extern int filp_close(struct file *, fl_owner_t id);
 extern char * getname(const char __user *);
 
+/**
+ * retry_estale - determine whether the caller should retry an operation
+ *
+ * @error: the error we'll be returning
+ * @try: number of retries already performed
+ *
+ * Check to see if the error code was -ESTALE, and then determine whether
+ * to retry the call based on the number of retries so far. Currently, we only
+ * retry the call once.
+ *
+ * Returns true if the caller should try again.
+ */
+static inline bool
+retry_estale(const long error, const unsigned int try)
+{
+	if (likely(error != -ESTALE))
+		return false;
+
+	return !try;
+}
+
 /* fs/ioctl.c */
 
 extern int ioctl_preallocate(struct file *filp, void __user *argp);
-- 
1.7.7.6

[PATCH v1 RESEND 02/12] vfs: make fstatat retry on ESTALE errors from getattr call

[Jeff Layton]

Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 fs/stat.c |   16 ++++++++++------
 1 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/fs/stat.c b/fs/stat.c
index c733dc5..f3eef0d 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -73,7 +73,8 @@ int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
 {
 	struct path path;
 	int error = -EINVAL;
-	int lookup_flags = 0;
+	unsigned int try = 0;
+	unsigned int lookup_flags = 0;
 
 	if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
 		      AT_EMPTY_PATH)) != 0)
@@ -84,12 +85,15 @@ int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
 	if (flag & AT_EMPTY_PATH)
 		lookup_flags |= LOOKUP_EMPTY;
 
-	error = user_path_at(dfd, filename, lookup_flags, &path);
-	if (error)
-		goto out;
+	do {
+		error = user_path_at(dfd, filename, lookup_flags, &path);
+		if (error)
+			break;
 
-	error = vfs_getattr(path.mnt, path.dentry, stat);
-	path_put(&path);
+		error = vfs_getattr(path.mnt, path.dentry, stat);
+		path_put(&path);
+		lookup_flags |= LOOKUP_REVAL;
+	} while (retry_estale(error, try++));
 out:
 	return error;
 }
-- 
1.7.7.6

[PATCH v1 RESEND 03/12] vfs: fix readlinkat to retry on ESTALE

[Jeff Layton]

Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 fs/stat.c |   16 ++++++++++++----
 1 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/fs/stat.c b/fs/stat.c
index f3eef0d..f7904aa 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -299,14 +299,21 @@ SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
 	struct path path;
 	int error;
 	int empty = 0;
+	unsigned int try = 0;
+	unsigned int lookup_flags = LOOKUP_EMPTY;
 
 	if (bufsiz <= 0)
 		return -EINVAL;
 
-	error = user_path_at_empty(dfd, pathname, LOOKUP_EMPTY, &path, &empty);
-	if (!error) {
-		struct inode *inode = path.dentry->d_inode;
+	do {
+		struct inode *inode;
+
+		error = user_path_at_empty(dfd, pathname, lookup_flags, &path,
+					   &empty);
+		if (error)
+			break;
 
+		inode = path.dentry->d_inode;
 		error = empty ? -ENOENT : -EINVAL;
 		if (inode->i_op->readlink) {
 			error = security_inode_readlink(path.dentry);
@@ -317,7 +324,8 @@ SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
 			}
 		}
 		path_put(&path);
-	}
+		lookup_flags |= LOOKUP_REVAL;
+	} while (retry_estale(error, try++));
 	return error;
 }
 
-- 
1.7.7.6

[PATCH v1 RESEND 04/12] vfs: add new "reval" argument to kern_path_create and user_path_create

[Jeff Layton]

...for now, all of the callers pass in "false". Eventually, we'll set
that to "true" when we retry the lookup after getting back an ESTALE on
a call.

While we're at it, change the is_dir arg to a bool since that's how
it's used currently.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 arch/powerpc/platforms/cell/spufs/syscalls.c |    2 +-
 drivers/base/devtmpfs.c                      |    7 ++++---
 fs/namei.c                                   |   22 ++++++++++++++--------
 fs/ocfs2/refcounttree.c                      |    3 ++-
 include/linux/namei.h                        |    4 ++--
 net/unix/af_unix.c                           |    3 ++-
 6 files changed, 25 insertions(+), 16 deletions(-)

diff --git a/arch/powerpc/platforms/cell/spufs/syscalls.c b/arch/powerpc/platforms/cell/spufs/syscalls.c
index 5665dcc..3c222cc 100644
--- a/arch/powerpc/platforms/cell/spufs/syscalls.c
+++ b/arch/powerpc/platforms/cell/spufs/syscalls.c
@@ -66,7 +66,7 @@ static long do_spu_create(const char __user *pathname, unsigned int flags,
 	struct dentry *dentry;
 	int ret;
 
-	dentry = user_path_create(AT_FDCWD, pathname, &path, 1);
+	dentry = user_path_create(AT_FDCWD, pathname, &path, true, false);
 	ret = PTR_ERR(dentry);
 	if (!IS_ERR(dentry)) {
 		ret = spufs_create(&path, dentry, flags, mode, neighbor);
diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
index 8493536..70eb0b0 100644
--- a/drivers/base/devtmpfs.c
+++ b/drivers/base/devtmpfs.c
@@ -148,7 +148,7 @@ static int dev_mkdir(const char *name, umode_t mode)
 	struct path path;
 	int err;
 
-	dentry = kern_path_create(AT_FDCWD, name, &path, 1);
+	dentry = kern_path_create(AT_FDCWD, name, &path, false, false);
 	if (IS_ERR(dentry))
 		return PTR_ERR(dentry);
 
@@ -195,10 +195,11 @@ static int handle_create(const char *nodename, umode_t mode, struct device *dev)
 	struct path path;
 	int err;
 
-	dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
+	dentry = kern_path_create(AT_FDCWD, nodename, &path, false, false);
 	if (dentry == ERR_PTR(-ENOENT)) {
 		create_path(nodename);
-		dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
+		dentry = kern_path_create(AT_FDCWD, nodename, &path,
+								false, false);
 	}
 	if (IS_ERR(dentry))
 		return PTR_ERR(dentry);
diff --git a/fs/namei.c b/fs/namei.c
index c427919..43e568b 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2460,11 +2460,17 @@ struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
 	return file;
 }
 
-struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir)
+struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, bool is_dir, bool reval)
 {
 	struct dentry *dentry = ERR_PTR(-EEXIST);
 	struct nameidata nd;
-	int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd);
+	int error;
+	unsigned int lookup_flags = LOOKUP_PARENT;
+
+	if (reval)
+		lookup_flags |= LOOKUP_REVAL;
+
+	error = do_path_lookup(dfd, pathname, lookup_flags, &nd);
 	if (error)
 		return ERR_PTR(error);
 
@@ -2512,13 +2518,13 @@ out:
 }
 EXPORT_SYMBOL(kern_path_create);
 
-struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir)
+struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, bool is_dir, bool reval)
 {
 	char *tmp = getname(pathname);
 	struct dentry *res;
 	if (IS_ERR(tmp))
 		return ERR_CAST(tmp);
-	res = kern_path_create(dfd, tmp, path, is_dir);
+	res = kern_path_create(dfd, tmp, path, is_dir, reval);
 	putname(tmp);
 	return res;
 }
@@ -2579,7 +2585,7 @@ SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode,
 	if (S_ISDIR(mode))
 		return -EPERM;
 
-	dentry = user_path_create(dfd, filename, &path, 0);
+	dentry = user_path_create(dfd, filename, &path, false, false);
 	if (IS_ERR(dentry))
 		return PTR_ERR(dentry);
 
@@ -2652,7 +2658,7 @@ SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode)
 	struct path path;
 	int error;
 
-	dentry = user_path_create(dfd, pathname, &path, 1);
+	dentry = user_path_create(dfd, pathname, &path, true, false);
 	if (IS_ERR(dentry))
 		return PTR_ERR(dentry);
 
@@ -2939,7 +2945,7 @@ SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
 	if (IS_ERR(from))
 		return PTR_ERR(from);
 
-	dentry = user_path_create(newdfd, newname, &path, 0);
+	dentry = user_path_create(newdfd, newname, &path, false, false);
 	error = PTR_ERR(dentry);
 	if (IS_ERR(dentry))
 		goto out_putname;
@@ -3048,7 +3054,7 @@ SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
 	if (error)
 		return error;
 
-	new_dentry = user_path_create(newdfd, newname, &new_path, 0);
+	new_dentry = user_path_create(newdfd, newname, &new_path, false, false);
 	error = PTR_ERR(new_dentry);
 	if (IS_ERR(new_dentry))
 		goto out;
diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 9f32d7c..b52b24d 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -4453,7 +4453,8 @@ int ocfs2_reflink_ioctl(struct inode *inode,
 		return error;
 	}
 
-	new_dentry = user_path_create(AT_FDCWD, newname, &new_path, 0);
+	new_dentry = user_path_create(AT_FDCWD, newname, &new_path,
+								false, false);
 	error = PTR_ERR(new_dentry);
 	if (IS_ERR(new_dentry)) {
 		mlog_errno(error);
diff --git a/include/linux/namei.h b/include/linux/namei.h
index ffc0213..3e90dcd 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -76,8 +76,8 @@ extern int user_path_at_empty(int, const char __user *, unsigned, struct path *,
 
 extern int kern_path(const char *, unsigned, struct path *);
 
-extern struct dentry *kern_path_create(int, const char *, struct path *, int);
-extern struct dentry *user_path_create(int, const char __user *, struct path *, int);
+extern struct dentry *kern_path_create(int, const char *, struct path *, bool, bool);
+extern struct dentry *user_path_create(int, const char __user *, struct path *, bool, bool);
 extern int kern_path_parent(const char *, struct nameidata *);
 extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
 			   const char *, unsigned int, struct path *);
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index d510353..9951294 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -865,7 +865,8 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 		 * Get the parent directory, calculate the hash for last
 		 * component.
 		 */
-		dentry = kern_path_create(AT_FDCWD, sun_path, &path, 0);
+		dentry = kern_path_create(AT_FDCWD, sun_path, &path,
+								false, false);
 		err = PTR_ERR(dentry);
 		if (IS_ERR(dentry))
 			goto out_mknod_parent;
-- 
1.7.7.6

[PATCH v1 RESEND 05/12] vfs: fix mknodat to retry on ESTALE errors

[Jeff Layton]

Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 fs/namei.c |   62 ++++++++++++++++++++++++++++++-----------------------------
 1 files changed, 32 insertions(+), 30 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 43e568b..471c038 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2581,44 +2581,46 @@ SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode,
 	struct dentry *dentry;
 	struct path path;
 	int error;
+	unsigned int try = 0;
 
 	if (S_ISDIR(mode))
 		return -EPERM;
 
-	dentry = user_path_create(dfd, filename, &path, false, false);
-	if (IS_ERR(dentry))
-		return PTR_ERR(dentry);
+	do {
+		dentry = user_path_create(dfd, filename, &path, false, try);
+		if (IS_ERR(dentry))
+			return PTR_ERR(dentry);
 
-	if (!IS_POSIXACL(path.dentry->d_inode))
-		mode &= ~current_umask();
-	error = may_mknod(mode);
-	if (error)
-		goto out_dput;
-	error = mnt_want_write(path.mnt);
-	if (error)
-		goto out_dput;
-	error = security_path_mknod(&path, dentry, mode, dev);
-	if (error)
-		goto out_drop_write;
-	switch (mode & S_IFMT) {
-		case 0: case S_IFREG:
-			error = vfs_create(path.dentry->d_inode,dentry,mode,NULL);
-			break;
-		case S_IFCHR: case S_IFBLK:
-			error = vfs_mknod(path.dentry->d_inode,dentry,mode,
-					new_decode_dev(dev));
-			break;
-		case S_IFIFO: case S_IFSOCK:
-			error = vfs_mknod(path.dentry->d_inode,dentry,mode,0);
+		if (!IS_POSIXACL(path.dentry->d_inode))
+			mode &= ~current_umask();
+		error = may_mknod(mode);
+		if (error)
+			goto out_dput;
+		error = mnt_want_write(path.mnt);
+		if (error)
+			goto out_dput;
+		error = security_path_mknod(&path, dentry, mode, dev);
+		if (error)
+			goto out_drop_write;
+		switch (mode & S_IFMT) {
+			case 0: case S_IFREG:
+				error = vfs_create(path.dentry->d_inode, dentry, mode, NULL);
+				break;
+			case S_IFCHR: case S_IFBLK:
+				error = vfs_mknod(path.dentry->d_inode, dentry, mode,
+						new_decode_dev(dev));
+				break;
+			case S_IFIFO: case S_IFSOCK:
+				error = vfs_mknod(path.dentry->d_inode, dentry, mode, 0);
 			break;
-	}
+		}
 out_drop_write:
-	mnt_drop_write(path.mnt);
+		mnt_drop_write(path.mnt);
 out_dput:
-	dput(dentry);
-	mutex_unlock(&path.dentry->d_inode->i_mutex);
-	path_put(&path);
-
+		dput(dentry);
+		mutex_unlock(&path.dentry->d_inode->i_mutex);
+		path_put(&path);
+	} while (retry_estale(error, try++));
 	return error;
 }
 
-- 
1.7.7.6

[PATCH v1 RESEND 06/12] vfs: fix mkdir to retry on ESTALE errors

[Jeff Layton]

Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 fs/namei.c |   38 +++++++++++++++++++++-----------------
 1 files changed, 21 insertions(+), 17 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 471c038..3238a82 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2659,26 +2659,30 @@ SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode)
 	struct dentry *dentry;
 	struct path path;
 	int error;
+	unsigned int try = 0;
 
-	dentry = user_path_create(dfd, pathname, &path, true, false);
-	if (IS_ERR(dentry))
-		return PTR_ERR(dentry);
-
-	if (!IS_POSIXACL(path.dentry->d_inode))
-		mode &= ~current_umask();
-	error = mnt_want_write(path.mnt);
-	if (error)
-		goto out_dput;
-	error = security_path_mkdir(&path, dentry, mode);
-	if (error)
-		goto out_drop_write;
-	error = vfs_mkdir(path.dentry->d_inode, dentry, mode);
+	do {
+		dentry = user_path_create(dfd, pathname, &path, true, try);
+		if (IS_ERR(dentry)) {
+			error = PTR_ERR(dentry);
+			break;
+		}
+		if (!IS_POSIXACL(path.dentry->d_inode))
+			mode &= ~current_umask();
+		error = mnt_want_write(path.mnt);
+		if (error)
+			goto out_dput;
+		error = security_path_mkdir(&path, dentry, mode);
+		if (error)
+			goto out_drop_write;
+		error = vfs_mkdir(path.dentry->d_inode, dentry, mode);
 out_drop_write:
-	mnt_drop_write(path.mnt);
+		mnt_drop_write(path.mnt);
 out_dput:
-	dput(dentry);
-	mutex_unlock(&path.dentry->d_inode->i_mutex);
-	path_put(&path);
+		dput(dentry);
+		mutex_unlock(&path.dentry->d_inode->i_mutex);
+		path_put(&path);
+	} while (retry_estale(error, try++));
 	return error;
 }
 
-- 
1.7.7.6

[PATCH v1 RESEND 07/12] vfs: add a "reval" flag to args for user_path_parent

[Jeff Layton]

All of the current callers set this to "false" for now, but we'll fix
them later to set it to true when they retry on an ESTALE error.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 fs/namei.c |   16 ++++++++++------
 1 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 3238a82..c8254de 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1908,15 +1908,19 @@ int user_path_at(int dfd, const char __user *name, unsigned flags,
 }
 
 static int user_path_parent(int dfd, const char __user *path,
-			struct nameidata *nd, char **name)
+			struct nameidata *nd, char **name, bool reval)
 {
 	char *s = getname(path);
 	int error;
+	unsigned int lookup_flags = LOOKUP_PARENT;
 
 	if (IS_ERR(s))
 		return PTR_ERR(s);
 
-	error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd);
+	if (reval)
+		lookup_flags |= LOOKUP_REVAL;
+
+	error = do_path_lookup(dfd, s, lookup_flags, nd);
 	if (error)
 		putname(s);
 	else
@@ -2759,7 +2763,7 @@ static long do_rmdir(int dfd, const char __user *pathname)
 	struct dentry *dentry;
 	struct nameidata nd;
 
-	error = user_path_parent(dfd, pathname, &nd, &name);
+	error = user_path_parent(dfd, pathname, &nd, &name, false);
 	if (error)
 		return error;
 
@@ -2856,7 +2860,7 @@ static long do_unlinkat(int dfd, const char __user *pathname)
 	struct nameidata nd;
 	struct inode *inode = NULL;
 
-	error = user_path_parent(dfd, pathname, &nd, &name);
+	error = user_path_parent(dfd, pathname, &nd, &name, false);
 	if (error)
 		return error;
 
@@ -3255,11 +3259,11 @@ SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
 	char *to;
 	int error;
 
-	error = user_path_parent(olddfd, oldname, &oldnd, &from);
+	error = user_path_parent(olddfd, oldname, &oldnd, &from, false);
 	if (error)
 		goto exit;
 
-	error = user_path_parent(newdfd, newname, &newnd, &to);
+	error = user_path_parent(newdfd, newname, &newnd, &to, false);
 	if (error)
 		goto exit1;
 
-- 
1.7.7.6

[PATCH v1 RESEND 08/12] vfs: make rmdir retry on ESTALE errors

[Jeff Layton]

Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 fs/namei.c |   76 +++++++++++++++++++++++++++++++----------------------------
 1 files changed, 40 insertions(+), 36 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index c8254de..58f5eae 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2762,50 +2762,54 @@ static long do_rmdir(int dfd, const char __user *pathname)
 	char * name;
 	struct dentry *dentry;
 	struct nameidata nd;
+	unsigned int try = 0;
 
-	error = user_path_parent(dfd, pathname, &nd, &name, false);
-	if (error)
-		return error;
+	do {
+		error = user_path_parent(dfd, pathname, &nd, &name, try);
+		if (error)
+			break;
 
-	switch(nd.last_type) {
-	case LAST_DOTDOT:
-		error = -ENOTEMPTY;
-		goto exit1;
-	case LAST_DOT:
-		error = -EINVAL;
-		goto exit1;
-	case LAST_ROOT:
-		error = -EBUSY;
-		goto exit1;
-	}
+		switch(nd.last_type) {
+		case LAST_DOTDOT:
+			error = -ENOTEMPTY;
+			goto exit1;
+		case LAST_DOT:
+			error = -EINVAL;
+			goto exit1;
+		case LAST_ROOT:
+			error = -EBUSY;
+			goto exit1;
+		}
 
-	nd.flags &= ~LOOKUP_PARENT;
+		nd.flags &= ~LOOKUP_PARENT;
 
-	mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
-	dentry = lookup_hash(&nd);
-	error = PTR_ERR(dentry);
-	if (IS_ERR(dentry))
-		goto exit2;
-	if (!dentry->d_inode) {
-		error = -ENOENT;
-		goto exit3;
-	}
-	error = mnt_want_write(nd.path.mnt);
-	if (error)
-		goto exit3;
-	error = security_path_rmdir(&nd.path, dentry);
-	if (error)
-		goto exit4;
-	error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
+		mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex,
+							I_MUTEX_PARENT);
+		dentry = lookup_hash(&nd);
+		error = PTR_ERR(dentry);
+		if (IS_ERR(dentry))
+			goto exit2;
+		if (!dentry->d_inode) {
+			error = -ENOENT;
+			goto exit3;
+		}
+		error = mnt_want_write(nd.path.mnt);
+		if (error)
+			goto exit3;
+		error = security_path_rmdir(&nd.path, dentry);
+		if (error)
+			goto exit4;
+		error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
 exit4:
-	mnt_drop_write(nd.path.mnt);
+		mnt_drop_write(nd.path.mnt);
 exit3:
-	dput(dentry);
+		dput(dentry);
 exit2:
-	mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
+		mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
 exit1:
-	path_put(&nd.path);
-	putname(name);
+		path_put(&nd.path);
+		putname(name);
+	} while (retry_estale(error, try++));
 	return error;
 }
 
-- 
1.7.7.6

[PATCH v1 RESEND 09/12] vfs: make do_unlinkat retry on ESTALE errors

[Jeff Layton]

Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 fs/namei.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 58f5eae..cee62f1 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2863,8 +2863,9 @@ static long do_unlinkat(int dfd, const char __user *pathname)
 	struct dentry *dentry;
 	struct nameidata nd;
 	struct inode *inode = NULL;
-
-	error = user_path_parent(dfd, pathname, &nd, &name, false);
+	unsigned int try = 0;
+retry:
+	error = user_path_parent(dfd, pathname, &nd, &name, try);
 	if (error)
 		return error;
 
@@ -2903,6 +2904,8 @@ exit3:
 exit1:
 	path_put(&nd.path);
 	putname(name);
+	if (retry_estale(error, try++))
+		goto retry;
 	return error;
 
 slashes:
-- 
1.7.7.6

[PATCH v1 RESEND 10/12] vfs: fix symlinkat to retry on ESTALE errors

[Jeff Layton]

Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 fs/namei.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index cee62f1..b5d28fe 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2957,12 +2957,14 @@ SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
 	char *from;
 	struct dentry *dentry;
 	struct path path;
+	unsigned int try = 0;
 
 	from = getname(oldname);
 	if (IS_ERR(from))
 		return PTR_ERR(from);
 
-	dentry = user_path_create(newdfd, newname, &path, false, false);
+retry:
+	dentry = user_path_create(newdfd, newname, &path, false, try);
 	error = PTR_ERR(dentry);
 	if (IS_ERR(dentry))
 		goto out_putname;
@@ -2980,6 +2982,8 @@ out_dput:
 	dput(dentry);
 	mutex_unlock(&path.dentry->d_inode->i_mutex);
 	path_put(&path);
+	if (retry_estale(error, try++))
+		goto retry;
 out_putname:
 	putname(from);
 	return error;
-- 
1.7.7.6

[PATCH v1 RESEND 11/12] vfs: fix linkat to retry on ESTALE errors

[Jeff Layton]

Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 fs/namei.c |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index b5d28fe..a40dcbb 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3054,6 +3054,7 @@ SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
 	struct path old_path, new_path;
 	int how = 0;
 	int error;
+	unsigned int try = 0;
 
 	if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0)
 		return -EINVAL;
@@ -3071,11 +3072,12 @@ SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
 	if (flags & AT_SYMLINK_FOLLOW)
 		how |= LOOKUP_FOLLOW;
 
+retry:
 	error = user_path_at(olddfd, oldname, how, &old_path);
 	if (error)
 		return error;
 
-	new_dentry = user_path_create(newdfd, newname, &new_path, false, false);
+	new_dentry = user_path_create(newdfd, newname, &new_path, false, try);
 	error = PTR_ERR(new_dentry);
 	if (IS_ERR(new_dentry))
 		goto out;
@@ -3098,7 +3100,10 @@ out_dput:
 	path_put(&new_path);
 out:
 	path_put(&old_path);
-
+	if (retry_estale(error, try++)) {
+		how |= LOOKUP_REVAL;
+		goto retry;
+	}
 	return error;
 }
 
-- 
1.7.7.6

[PATCH v1 RESEND 12/12] vfs: fix renameat to retry on ESTALE errors

[Jeff Layton]

...as always, rename is the messiest of the bunch...

Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 fs/namei.c |   13 +++++++++++--
 1 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index a40dcbb..3e15aea 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3274,12 +3274,15 @@ SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
 	char *from;
 	char *to;
 	int error;
+	unsigned int try = 0;
+	bool should_retry = false;
 
-	error = user_path_parent(olddfd, oldname, &oldnd, &from, false);
+retry:
+	error = user_path_parent(olddfd, oldname, &oldnd, &from, try);
 	if (error)
 		goto exit;
 
-	error = user_path_parent(newdfd, newname, &newnd, &to, false);
+	error = user_path_parent(newdfd, newname, &newnd, &to, try);
 	if (error)
 		goto exit1;
 
@@ -3348,12 +3351,18 @@ exit4:
 	dput(old_dentry);
 exit3:
 	unlock_rename(new_dir, old_dir);
+	if (retry_estale(error, try++))
+		should_retry = true;
 exit2:
 	path_put(&newnd.path);
 	putname(to);
 exit1:
 	path_put(&oldnd.path);
 	putname(from);
+	if (should_retry) {
+		should_retry = false;
+		goto retry;
+	}
 exit:
 	return error;
 }
-- 
1.7.7.6

Re: [PATCH v1 RESEND 04/12] vfs: add new "reval" argument to kern_path_create and user_path_create

[Jeff Layton]

On Mon,  7 May 2012 10:12:03 -0400
Jeff Layton <jlayton@redhat.com> wrote:

> ...for now, all of the callers pass in "false". Eventually, we'll set
> that to "true" when we retry the lookup after getting back an ESTALE on
> a call.
> 
> While we're at it, change the is_dir arg to a bool since that's how
> it's used currently.
> 
> Signed-off-by: Jeff Layton <jlayton@redhat.com>
> ---
>  arch/powerpc/platforms/cell/spufs/syscalls.c |    2 +-
>  drivers/base/devtmpfs.c                      |    7 ++++---
>  fs/namei.c                                   |   22 ++++++++++++++--------
>  fs/ocfs2/refcounttree.c                      |    3 ++-
>  include/linux/namei.h                        |    4 ++--
>  net/unix/af_unix.c                           |    3 ++-
>  6 files changed, 25 insertions(+), 16 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/cell/spufs/syscalls.c b/arch/powerpc/platforms/cell/spufs/syscalls.c
> index 5665dcc..3c222cc 100644
> --- a/arch/powerpc/platforms/cell/spufs/syscalls.c
> +++ b/arch/powerpc/platforms/cell/spufs/syscalls.c
> @@ -66,7 +66,7 @@ static long do_spu_create(const char __user *pathname, unsigned int flags,
>  	struct dentry *dentry;
>  	int ret;
>  
> -	dentry = user_path_create(AT_FDCWD, pathname, &path, 1);
> +	dentry = user_path_create(AT_FDCWD, pathname, &path, true, false);
>  	ret = PTR_ERR(dentry);
>  	if (!IS_ERR(dentry)) {
>  		ret = spufs_create(&path, dentry, flags, mode, neighbor);
> diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
> index 8493536..70eb0b0 100644
> --- a/drivers/base/devtmpfs.c
> +++ b/drivers/base/devtmpfs.c
> @@ -148,7 +148,7 @@ static int dev_mkdir(const char *name, umode_t mode)
>  	struct path path;
>  	int err;
>  
> -	dentry = kern_path_create(AT_FDCWD, name, &path, 1);
> +	dentry = kern_path_create(AT_FDCWD, name, &path, false, false);

Peter Staubach pointed out to me that I flipped the above "is_dir" flag
from true to false. I've fixed this in my patch stack so the next respin
should have that fixed.

>  	if (IS_ERR(dentry))
>  		return PTR_ERR(dentry);
>  
> @@ -195,10 +195,11 @@ static int handle_create(const char *nodename, umode_t mode, struct device *dev)
>  	struct path path;
>  	int err;
>  
> -	dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
> +	dentry = kern_path_create(AT_FDCWD, nodename, &path, false, false);
>  	if (dentry == ERR_PTR(-ENOENT)) {
>  		create_path(nodename);
> -		dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
> +		dentry = kern_path_create(AT_FDCWD, nodename, &path,
> +								false, false);
>  	}
>  	if (IS_ERR(dentry))
>  		return PTR_ERR(dentry);
> diff --git a/fs/namei.c b/fs/namei.c
> index c427919..43e568b 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -2460,11 +2460,17 @@ struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
>  	return file;
>  }
>  
> -struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir)
> +struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, bool is_dir, bool reval)
>  {
>  	struct dentry *dentry = ERR_PTR(-EEXIST);
>  	struct nameidata nd;
> -	int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd);
> +	int error;
> +	unsigned int lookup_flags = LOOKUP_PARENT;
> +
> +	if (reval)
> +		lookup_flags |= LOOKUP_REVAL;
> +
> +	error = do_path_lookup(dfd, pathname, lookup_flags, &nd);
>  	if (error)
>  		return ERR_PTR(error);
>  
> @@ -2512,13 +2518,13 @@ out:
>  }
>  EXPORT_SYMBOL(kern_path_create);
>  
> -struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir)
> +struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, bool is_dir, bool reval)
>  {
>  	char *tmp = getname(pathname);
>  	struct dentry *res;
>  	if (IS_ERR(tmp))
>  		return ERR_CAST(tmp);
> -	res = kern_path_create(dfd, tmp, path, is_dir);
> +	res = kern_path_create(dfd, tmp, path, is_dir, reval);
>  	putname(tmp);
>  	return res;
>  }
> @@ -2579,7 +2585,7 @@ SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode,
>  	if (S_ISDIR(mode))
>  		return -EPERM;
>  
> -	dentry = user_path_create(dfd, filename, &path, 0);
> +	dentry = user_path_create(dfd, filename, &path, false, false);
>  	if (IS_ERR(dentry))
>  		return PTR_ERR(dentry);
>  
> @@ -2652,7 +2658,7 @@ SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode)
>  	struct path path;
>  	int error;
>  
> -	dentry = user_path_create(dfd, pathname, &path, 1);
> +	dentry = user_path_create(dfd, pathname, &path, true, false);
>  	if (IS_ERR(dentry))
>  		return PTR_ERR(dentry);
>  
> @@ -2939,7 +2945,7 @@ SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
>  	if (IS_ERR(from))
>  		return PTR_ERR(from);
>  
> -	dentry = user_path_create(newdfd, newname, &path, 0);
> +	dentry = user_path_create(newdfd, newname, &path, false, false);
>  	error = PTR_ERR(dentry);
>  	if (IS_ERR(dentry))
>  		goto out_putname;
> @@ -3048,7 +3054,7 @@ SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
>  	if (error)
>  		return error;
>  
> -	new_dentry = user_path_create(newdfd, newname, &new_path, 0);
> +	new_dentry = user_path_create(newdfd, newname, &new_path, false, false);
>  	error = PTR_ERR(new_dentry);
>  	if (IS_ERR(new_dentry))
>  		goto out;
> diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
> index 9f32d7c..b52b24d 100644
> --- a/fs/ocfs2/refcounttree.c
> +++ b/fs/ocfs2/refcounttree.c
> @@ -4453,7 +4453,8 @@ int ocfs2_reflink_ioctl(struct inode *inode,
>  		return error;
>  	}
>  
> -	new_dentry = user_path_create(AT_FDCWD, newname, &new_path, 0);
> +	new_dentry = user_path_create(AT_FDCWD, newname, &new_path,
> +								false, false);
>  	error = PTR_ERR(new_dentry);
>  	if (IS_ERR(new_dentry)) {
>  		mlog_errno(error);
> diff --git a/include/linux/namei.h b/include/linux/namei.h
> index ffc0213..3e90dcd 100644
> --- a/include/linux/namei.h
> +++ b/include/linux/namei.h
> @@ -76,8 +76,8 @@ extern int user_path_at_empty(int, const char __user *, unsigned, struct path *,
>  
>  extern int kern_path(const char *, unsigned, struct path *);
>  
> -extern struct dentry *kern_path_create(int, const char *, struct path *, int);
> -extern struct dentry *user_path_create(int, const char __user *, struct path *, int);
> +extern struct dentry *kern_path_create(int, const char *, struct path *, bool, bool);
> +extern struct dentry *user_path_create(int, const char __user *, struct path *, bool, bool);
>  extern int kern_path_parent(const char *, struct nameidata *);
>  extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
>  			   const char *, unsigned int, struct path *);
> diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
> index d510353..9951294 100644
> --- a/net/unix/af_unix.c
> +++ b/net/unix/af_unix.c
> @@ -865,7 +865,8 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
>  		 * Get the parent directory, calculate the hash for last
>  		 * component.
>  		 */
> -		dentry = kern_path_create(AT_FDCWD, sun_path, &path, 0);
> +		dentry = kern_path_create(AT_FDCWD, sun_path, &path,
> +								false, false);
>  		err = PTR_ERR(dentry);
>  		if (IS_ERR(dentry))
>  			goto out_mknod_parent;


-- 
Jeff Layton <jlayton@redhat.com>