NFSv3: Fix posix ACL code

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From: Linux Kernel Mailing List
Date: Saturday, March 14, 2009 - 1:00 pm

Gitweb:     http://git.kernel.org/linus/ae46141ff08f1965b17c531b571953c39ce8b9e2
Commit:     ae46141ff08f1965b17c531b571953c39ce8b9e2
Parent:     ef95d31e6de6be9602ce950b85fb7ab8af46ae42
Author:     Trond Myklebust <Trond.Myklebust@netapp.com>
AuthorDate: Tue Mar 10 20:33:18 2009 -0400
Committer:  Trond Myklebust <Trond.Myklebust@netapp.com>
CommitDate: Tue Mar 10 20:33:18 2009 -0400

    NFSv3: Fix posix ACL code
    
    Fix a memory leak due to allocation in the XDR layer. In cases where the
    RPC call needs to be retransmitted, we end up allocating new pages without
    clearing the old ones. Fix this by moving the allocation into
    nfs3_proc_setacls().
    
    Also fix an issue discovered by Kevin Rudd, whereby the amount of memory
    reserved for the acls in the xdr_buf->head was miscalculated, and causing
    corruption.
    
    Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
---
 fs/nfs/nfs3acl.c        |   27 +++++++++++++++++++++------
 fs/nfs/nfs3xdr.c        |   34 +++++++++++++---------------------
 include/linux/nfs_xdr.h |    2 ++
 include/linux/nfsacl.h  |    3 +++
 4 files changed, 39 insertions(+), 27 deletions(-)

diff --git a/fs/nfs/nfs3acl.c b/fs/nfs/nfs3acl.c
index cef6255..6bbf0e6 100644
--- a/fs/nfs/nfs3acl.c
+++ b/fs/nfs/nfs3acl.c
@@ -292,7 +292,7 @@ static int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 {
 	struct nfs_server *server = NFS_SERVER(inode);
 	struct nfs_fattr fattr;
-	struct page *pages[NFSACL_MAXPAGES] = { };
+	struct page *pages[NFSACL_MAXPAGES];
 	struct nfs3_setaclargs args = {
 		.inode = inode,
 		.mask = NFS_ACL,
@@ -303,7 +303,7 @@ static int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 		.rpc_argp	= &args,
 		.rpc_resp	= &fattr,
 	};
-	int status, count;
+	int status;
 
 	status = -EOPNOTSUPP;
 	if (!nfs_server_capable(inode, NFS_CAP_ACLS))
@@ -319,6 +319,20 @@ static int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 	if (S_ISDIR(inode->i_mode)) {
 		args.mask |= NFS_DFACL;
 		args.acl_default = dfacl;
+		args.len = nfsacl_size(acl, dfacl);
+	} else
+		args.len = nfsacl_size(acl, NULL);
+
+	if (args.len > NFS_ACL_INLINE_BUFSIZE) {
+		unsigned int npages = 1 + ((args.len - 1) >> PAGE_SHIFT);
+
+		status = -ENOMEM;
+		do {
+			args.pages[args.npages] = alloc_page(GFP_KERNEL);
+			if (args.pages[args.npages] == NULL)
+				goto out_freepages;
+			args.npages++;
+		} while (args.npages < npages);
 	}
 
 	dprintk("NFS call setacl\n");
@@ -329,10 +343,6 @@ static int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 	nfs_zap_acl_cache(inode);
 	dprintk("NFS reply setacl: %d\n", status);
 
-	/* pages may have been allocated at the xdr layer. */
-	for (count = 0; count < NFSACL_MAXPAGES && args.pages[count]; count++)
-		__free_page(args.pages[count]);
-
 	switch (status) {
 		case 0:
 			status = nfs_refresh_inode(inode, &fattr);
@@ -346,6 +356,11 @@ static int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 		case -ENOTSUPP:
 			status = -EOPNOTSUPP;
 	}
+out_freepages:
+	while (args.npages != 0) {
+		args.npages--;
+		__free_page(args.pages[args.npages]);
+	}
 out:
 	return status;
 }
diff --git a/fs/nfs/nfs3xdr.c b/fs/nfs/nfs3xdr.c
index 11cddde..6cdeacf 100644
--- a/fs/nfs/nfs3xdr.c
+++ b/fs/nfs/nfs3xdr.c
@@ -82,8 +82,10 @@
 #define NFS3_commitres_sz	(1+NFS3_wcc_data_sz+2)
 
 #define ACL3_getaclargs_sz	(NFS3_fh_sz+1)
-#define ACL3_setaclargs_sz	(NFS3_fh_sz+1+2*(2+5*3))
-#define ACL3_getaclres_sz	(1+NFS3_post_op_attr_sz+1+2*(2+5*3))
+#define ACL3_setaclargs_sz	(NFS3_fh_sz+1+ \
+				XDR_QUADLEN(NFS_ACL_INLINE_BUFSIZE))
+#define ACL3_getaclres_sz	(1+NFS3_post_op_attr_sz+1+ \
+				XDR_QUADLEN(NFS_ACL_INLINE_BUFSIZE))
 #define ACL3_setaclres_sz	(1+NFS3_post_op_attr_sz)
 
 /*
@@ -703,28 +705,18 @@ nfs3_xdr_setaclargs(struct rpc_rqst *req, __be32 *p,
                    struct nfs3_setaclargs *args)
 {
 	struct xdr_buf *buf = &req->rq_snd_buf;
-	unsigned int base, len_in_head, len = nfsacl_size(
-		(args->mask & NFS_ACL)   ? args->acl_access  : NULL,
-		(args->mask & NFS_DFACL) ? args->acl_default : NULL);
-	int count, err;
+	unsigned int base;
+	int err;
 
 	p = xdr_encode_fhandle(p, NFS_FH(args->inode));
 	*p++ = htonl(args->mask);
-	base = (char *)p - (char *)buf->head->iov_base;
-	/* put as much of the acls into head as possible. */
-	len_in_head = min_t(unsigned int, buf->head->iov_len - base, len);
-	len -= len_in_head;
-	req->rq_slen = xdr_adjust_iovec(req->rq_svec, p + (len_in_head >> 2));
-
-	for (count = 0; (count << PAGE_SHIFT) < len; count++) {
-		args->pages[count] = alloc_page(GFP_KERNEL);
-		if (!args->pages[count]) {
-			while (count)
-				__free_page(args->pages[--count]);
-			return -ENOMEM;
-		}
-	}
-	xdr_encode_pages(buf, args->pages, 0, len);
+	req->rq_slen = xdr_adjust_iovec(req->rq_svec, p);
+	base = req->rq_slen;
+
+	if (args->npages != 0)
+		xdr_encode_pages(buf, args->pages, 0, args->len);
+	else
+		req->rq_slen += args->len;
 
 	err = nfsacl_encode(buf, base, args->inode,
 			    (args->mask & NFS_ACL) ?
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index a550b52..2e5f000 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -406,6 +406,8 @@ struct nfs3_setaclargs {
 	int			mask;
 	struct posix_acl *	acl_access;
 	struct posix_acl *	acl_default;
+	size_t			len;
+	unsigned int		npages;
 	struct page **		pages;
 };
 
diff --git a/include/linux/nfsacl.h b/include/linux/nfsacl.h
index 54487a9..43011b6 100644
--- a/include/linux/nfsacl.h
+++ b/include/linux/nfsacl.h
@@ -37,6 +37,9 @@
 #define NFSACL_MAXPAGES		((2*(8+12*NFS_ACL_MAX_ENTRIES) + PAGE_SIZE-1) \
 				 >> PAGE_SHIFT)
 
+#define NFS_ACL_MAX_ENTRIES_INLINE	(5)
+#define NFS_ACL_INLINE_BUFSIZE	((2*(2+3*NFS_ACL_MAX_ENTRIES_INLINE)) << 2)
+
 static inline unsigned int
 nfsacl_size(struct posix_acl *acl_access, struct posix_acl *acl_default)
 {
--
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NFSv3: Fix posix ACL code, Linux Kernel Mailing ..., (Sat Mar 14, 1:00 pm)