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From: Frank van der Linden <fllinden@amazon.com>
To: <linux-nfs@vger.kernel.org>, <linux-fsdevel@vger.kernel.org>
Subject: [RFC PATCH 21/35] xattr: modify vfs_{set,remove}xattr for NFS server use
Date: Sat, 31 Aug 2019 02:12:53 +0000
Message-ID: <2afeb5330f488b70f7ae5495b2b0d56e75ee9392.1568309119.git.fllinden@amazon.com> (raw)
In-Reply-To: <cover.1568309119.git.fllinden@amazon.com>

To be called from the upcoming NFS server xattr code, the vfs_removexattr
and vfs_setxattr need some modifications.

First, they need to grow a _locked variant, since the NFS server code
will call this with i_rwsem held. It needs to do that in fh_lock to be
able to atomically provide the before and after change attributes.

Second, RFC 8276 (NFSv4 extended attribute support) specifies that
delegations should be recalled (8.4.2.4, 8.4.4.4) when a SETXATTR
or REMOVEXATTR operation is performed. So, like with other fs
operations, try to break the delegation. The _locked version of
these operations will not wait for the delegation to be successfully
broken, instead returning an error if it wasn't, so that the NFS
server code can return NFS4ERR_DELAY to the client (similar to
what e.g. vfs_link does).

Signed-off-by: Frank van der Linden <fllinden@amazon.com>
---
 fs/xattr.c            | 63 ++++++++++++++++++++++++++++++++++++++-----
 include/linux/xattr.h |  2 ++
 2 files changed, 58 insertions(+), 7 deletions(-)

diff --git a/fs/xattr.c b/fs/xattr.c
index 90dd78f0eb27..58013bcbc333 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -204,10 +204,10 @@ int __vfs_setxattr_noperm(struct dentry *dentry, const char *name,
 	return error;
 }
 
-
 int
-vfs_setxattr(struct dentry *dentry, const char *name, const void *value,
-		size_t size, int flags)
+__vfs_setxattr_locked(struct dentry *dentry, const char *name,
+		const void *value, size_t size, int flags,
+		struct inode **delegated_inode)
 {
 	struct inode *inode = dentry->d_inode;
 	int error;
@@ -216,15 +216,40 @@ vfs_setxattr(struct dentry *dentry, const char *name, const void *value,
 	if (error)
 		return error;
 
-	inode_lock(inode);
 	error = security_inode_setxattr(dentry, name, value, size, flags);
 	if (error)
 		goto out;
 
+	error = try_break_deleg(inode, delegated_inode);
+	if (error)
+		goto out;
+
 	error = __vfs_setxattr_noperm(dentry, name, value, size, flags);
 
 out:
+	return error;
+}
+EXPORT_SYMBOL_GPL(__vfs_setxattr_locked);
+
+int
+vfs_setxattr(struct dentry *dentry, const char *name, const void *value,
+		size_t size, int flags)
+{
+	struct inode *inode = dentry->d_inode;
+	struct inode *delegated_inode = NULL;
+	int error;
+
+retry_deleg:
+	inode_lock(inode);
+	error = __vfs_setxattr_locked(dentry, name, value, size, flags,
+	    &delegated_inode);
 	inode_unlock(inode);
+
+	if (delegated_inode) {
+		error = break_deleg_wait(&delegated_inode);
+		if (!error)
+			goto retry_deleg;
+	}
 	return error;
 }
 EXPORT_SYMBOL_GPL(vfs_setxattr);
@@ -379,7 +404,8 @@ __vfs_removexattr(struct dentry *dentry, const char *name)
 EXPORT_SYMBOL(__vfs_removexattr);
 
 int
-vfs_removexattr(struct dentry *dentry, const char *name)
+__vfs_removexattr_locked(struct dentry *dentry, const char *name,
+		struct inode **delegated_inode)
 {
 	struct inode *inode = dentry->d_inode;
 	int error;
@@ -388,11 +414,14 @@ vfs_removexattr(struct dentry *dentry, const char *name)
 	if (error)
 		return error;
 
-	inode_lock(inode);
 	error = security_inode_removexattr(dentry, name);
 	if (error)
 		goto out;
 
+	error = try_break_deleg(inode, delegated_inode);
+	if (error)
+		goto out;
+
 	error = __vfs_removexattr(dentry, name);
 
 	if (!error) {
@@ -401,12 +430,32 @@ vfs_removexattr(struct dentry *dentry, const char *name)
 	}
 
 out:
+	return error;
+}
+EXPORT_SYMBOL_GPL(__vfs_removexattr_locked);
+
+int
+vfs_removexattr(struct dentry *dentry, const char *name)
+{
+	struct inode *inode = dentry->d_inode;
+	struct inode *delegated_inode = NULL;
+	int error;
+
+retry_deleg:
+	inode_lock(inode);
+	error = __vfs_removexattr_locked(dentry, name, &delegated_inode);
 	inode_unlock(inode);
+
+	if (delegated_inode) {
+		error = break_deleg_wait(&delegated_inode);
+		if (!error)
+			goto retry_deleg;
+	}
+
 	return error;
 }
 EXPORT_SYMBOL_GPL(vfs_removexattr);
 
-
 /*
  * Extended attribute SET operations
  */
diff --git a/include/linux/xattr.h b/include/linux/xattr.h
index 6dad031be3c2..3a71ad716da5 100644
--- a/include/linux/xattr.h
+++ b/include/linux/xattr.h
@@ -51,8 +51,10 @@ ssize_t vfs_getxattr(struct dentry *, const char *, void *, size_t);
 ssize_t vfs_listxattr(struct dentry *d, char *list, size_t size);
 int __vfs_setxattr(struct dentry *, struct inode *, const char *, const void *, size_t, int);
 int __vfs_setxattr_noperm(struct dentry *, const char *, const void *, size_t, int);
+int __vfs_setxattr_locked(struct dentry *, const char *, const void *, size_t, int, struct inode **);
 int vfs_setxattr(struct dentry *, const char *, const void *, size_t, int);
 int __vfs_removexattr(struct dentry *, const char *);
+int __vfs_removexattr_locked(struct dentry *, const char *, struct inode **);
 int vfs_removexattr(struct dentry *, const char *);
 
 ssize_t generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size);
-- 
2.17.2


  parent reply index

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-12 17:25 [RFC PATCH 00/35] user xattr support (RFC8276) Frank van der Linden
2019-07-01 17:56 ` [RFC PATCH 02/35] nfs/nfsd: basic NFS4 extended attribute definitions Frank van der Linden
2019-08-26 21:38 ` [RFC PATCH 03/35] NFSv4.2: query the server for extended attribute support Frank van der Linden
2019-08-26 21:53 ` [RFC PATCH 04/35] nfs: parse the {no}user_xattr option Frank van der Linden
2019-08-26 22:06 ` [RFC PATCH 05/35] NFSv4.2: define a function to compute the maximum XDR size for listxattr Frank van der Linden
2019-08-26 22:23 ` [RFC PATCH 06/35] NFSv4.2: define and set initial limits for extended attributes Frank van der Linden
2019-08-26 22:32 ` [RFC PATCH 07/35] NFSv4.2: define argument and response structures for xattr operations Frank van der Linden
2019-08-26 22:44 ` [RFC PATCH 08/35] NFSv4.2: define the encode/decode sizes for the XATTR operations Frank van der Linden
2019-08-26 23:09 ` [RFC PATCH 09/35] NFSv4.2: define and use extended attribute overhead sizes Frank van der Linden
2019-08-27 15:34 ` [RFC PATCH 10/35] NFSv4.2: add client side XDR handling for extended attributes Frank van der Linden
2019-08-27 15:46 ` [RFC PATCH 11/35] nfs: define nfs_access_get_cached function Frank van der Linden
2019-08-27 16:01 ` [RFC PATCH 12/35] NFSv4.2: query the extended attribute access bits Frank van der Linden
2019-08-27 22:51 ` [RFC PATCH 13/35] nfs: modify update_changeattr to deal with regular files Frank van der Linden
2019-08-30 22:48 ` [RFC PATCH 14/35] nfs: define and use the NFS_INO_INVALID_XATTR flag Frank van der Linden
2019-08-30 22:56 ` [RFC PATCH 15/35] nfs: make the buf_to_pages_noslab function available to the nfs code Frank van der Linden
2019-08-30 23:15 ` [RFC PATCH 16/35] NFSv4.2: add the extended attribute proc functions Frank van der Linden
2019-08-30 23:31 ` [RFC PATCH 17/35] NFSv4.2: hook in the user extended attribute handlers Frank van der Linden
2019-08-30 23:38 ` [RFC PATCH 18/35] NFSv4.2: add client side xattr caching functions Frank van der Linden
2019-08-30 23:45 ` [RFC PATCH 19/35] NFSv4.2: call the xattr cache functions Frank van der Linden
2019-08-30 23:59 ` [RFC PATCH 20/35] nfs: add the NFS_V4_XATTR config option Frank van der Linden
2019-08-31  2:12 ` Frank van der Linden [this message]
2019-08-31 19:00 ` [RFC PATCH 22/35] nfsd: split off the write decode code in to a seperate function Frank van der Linden
2019-08-31 19:19 ` [RFC PATCH 23/35] nfsd: add defines for NFSv4.2 extended attribute support Frank van der Linden
2019-08-31 21:35 ` [RFC PATCH 26/35] nfsd: add structure definitions for xattr requests / responses Frank van der Linden
2019-08-31 23:53 ` [RFC PATCH 24/35] nfsd: define xattr functions to call in to their vfs counterparts Frank van der Linden
2019-09-01  0:13 ` [RFC PATCH 25/35] nfsd: take xattr access bits in to account when checking Frank van der Linden
2019-09-01  1:19 ` [RFC PATCH 27/35] nfsd: implement the xattr procedure functions Frank van der Linden
2019-09-01  2:46 ` [RFC PATCH 01/35] nfsd: make sure the nfsd4_ops array has the right size Frank van der Linden
2019-09-02 19:40 ` [RFC PATCH 28/35] nfsd: define xattr reply size functions Frank van der Linden
2019-09-02 19:58 ` [RFC PATCH 29/35] nfsd: add xattr XDR decode functions Frank van der Linden
2019-09-02 20:09 ` [RFC PATCH 30/35] nfsd: add xattr XDR encode functions Frank van der Linden
2019-09-02 20:19 ` [RFC PATCH 31/35] nfsd: add xattr operations to ops array Frank van der Linden
2019-09-02 20:34 ` [RFC PATCH 32/35] xattr: add a function to check if a namespace is supported Frank van der Linden
2019-09-02 21:30 ` [RFC PATCH 33/35] nfsd: add fattr support for user extended attributes Frank van der Linden
2019-09-02 23:06 ` [RFC PATCH 34/35] nfsd: add export flag to disable " Frank van der Linden
2019-09-02 23:17 ` [RFC PATCH 35/35] nfsd: add NFSD_V4_XATTR config option Frank van der Linden
2019-10-24 20:16 ` [RFC PATCH 00/35] user xattr support (RFC8276) Chuck Lever
2019-10-24 23:15   ` Frank van der Linden
2019-10-25 19:55     ` Chuck Lever
2019-11-04  3:01       ` bfields
2019-11-04 15:36         ` Chuck Lever
2019-11-04 16:21           ` Frank van der Linden
2019-11-04 22:58             ` Bruce Fields
2019-11-05  0:06               ` Frank van der Linden
2019-11-05 15:44               ` Chuck Lever

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