commit e916e9e47a6a932872641d0da1f7bd4927b63fee

Author: Steve Dickson <steved@redhat.com>

Date:   Mon Aug 13 11:04:02 2007 -0400

    Adds support for the 'nosharecache' mount option to nfs-utils.

    Signed-off-by: Steve Dickson <steved@redhat.com>

diff --git a/utils/mount/nfs.man b/utils/mount/nfs.man

index 673556c..e66daba 100644

--- a/utils/mount/nfs.man

+++ b/utils/mount/nfs.man

@@ -288,6 +288,23 @@ Mount the NFS filesystem using the UDP protocol.

 Disables NFSv3 READDIRPLUS RPCs. Use this option when

 mounting servers that don't support or have broken

 READDIRPLUS implementations.

+.TP 1.5i

+.I nosharecache

+As of kernel 2.6.18, it is no longer possible to mount the same

+same filesystem with different mount options to a new mountpoint.

+It was deemed unsafe to do so, since cached data cannot be shared

+between the two mountpoints. In consequence, files or directories

+that were common to both mountpoint subtrees could often be seen to

+be out of sync following an update.

+.br

+This option allows administrators to select the pre-2.6.18 behaviour,

+permitting the same filesystem to be mounted with different mount

+options.

+.br

+.B Beware:

+Use of this option is not recommended unless you are certain that there

+are no hard links or subtrees of this mountpoint that are mounted

+elsewhere.

 .P

 All of the non-value options have corresponding nooption forms.

 For example, nointr means don't allow file operations to be

@@ -444,6 +461,23 @@ This extracts a

 server performance penalty but it allows two different NFS clients

 to get reasonable good results when both clients are actively

 writing to common filesystem on the server.

+.TP 1.5i

+.I nosharecache

+As of kernel 2.6.18, it is no longer possible to mount the same

+same filesystem with different mount options to a new mountpoint.

+It was deemed unsafe to do so, since cached data cannot be shared

+between the two mountpoints. In consequence, files or directories

+that were common to both mountpoint subtrees could often be seen to

+be out of sync following an update.

+.br

+This option allows administrators to select the pre-2.6.18 behaviour,

+permitting the same filesystem to be mounted with different mount

+options.

+.br

+.B Beware:

+Use of this option is not recommended unless you are certain that there

+are no hard links or subtrees of this mountpoint that are mounted

+elsewhere.

 .P

 All of the non-value options have corresponding nooption forms.

 For example, nointr means don't allow file operations to be

diff --git a/utils/mount/nfs4_mount.h b/utils/mount/nfs4_mount.h

index 74c9b95..2fcca6d 100644

--- a/utils/mount/nfs4_mount.h

+++ b/utils/mount/nfs4_mount.h

@@ -65,6 +65,7 @@ struct nfs4_mount_data {

 #define NFS4_MOUNT_NOCTO	0x0010	/* 1 */

 #define NFS4_MOUNT_NOAC		0x0020	/* 1 */

 #define NFS4_MOUNT_STRICTLOCK	0x1000	/* 1 */

+#define NFS4_MOUNT_UNSHARED	0x8000	/* 5 */

 #define NFS4_MOUNT_FLAGMASK	0xFFFF

 /* pseudoflavors: */

diff --git a/utils/mount/nfs4mount.c b/utils/mount/nfs4mount.c

index 2a58d0a..0376f32 100644

--- a/utils/mount/nfs4mount.c

+++ b/utils/mount/nfs4mount.c

@@ -201,7 +201,7 @@ int nfs4mount(const char *spec, const char *node, int *flags,

 	char *s;

 	int val;

 	int bg, soft, intr;

-	int nocto, noac;

+	int nocto, noac, unshared;

 	int retry;

 	int retval;

 	time_t timeout, t;

@@ -252,6 +252,7 @@ int nfs4mount(const char *spec, const char *node, int *flags,

 	intr = NFS4_MOUNT_INTR;

 	nocto = 0;

 	noac = 0;

+	unshared = 0;

 	retry = 10000;		/* 10000 minutes ~ 1 week */

 	/*

@@ -336,6 +337,8 @@ int nfs4mount(const char *spec, const char *node, int *flags,

 				nocto = !val;

 			else if (!strcmp(opt, "ac"))

 				noac = !val;

+			else if (!strcmp(opt, "sharecache"))

+				unshared = !val;

 			else if (!sloppy) {

 				printf(_("unknown nfs mount option: "

 					 "%s%s\n"), val ? "" : "no", opt);

@@ -347,7 +350,8 @@ int nfs4mount(const char *spec, const char *node, int *flags,

 	data.flags = (soft ? NFS4_MOUNT_SOFT : 0)

 		| (intr ? NFS4_MOUNT_INTR : 0)

 		| (nocto ? NFS4_MOUNT_NOCTO : 0)

-		| (noac ? NFS4_MOUNT_NOAC : 0);

+		| (noac ? NFS4_MOUNT_NOAC : 0)

+		| (unshared ? NFS4_MOUNT_UNSHARED : 0);

 	/*

 	 * Give a warning if the rpc.idmapd daemon is not running

@@ -388,11 +392,13 @@ int nfs4mount(const char *spec, const char *node, int *flags,

 	       data.acregmin, data.acregmax, data.acdirmin, data.acdirmax);

 	printf("port = %d, bg = %d, retry = %d, flags = %.8x\n",

 	       ntohs(server_addr.sin_port), bg, retry, data.flags);

-	printf("soft = %d, intr = %d, nocto = %d, noac = %d\n",

+	printf("soft = %d, intr = %d, nocto = %d, noac = %d, "

+	       "nosharecache = %d\n",

 	       (data.flags & NFS4_MOUNT_SOFT) != 0,

 	       (data.flags & NFS4_MOUNT_INTR) != 0,

 	       (data.flags & NFS4_MOUNT_NOCTO) != 0,

-	       (data.flags & NFS4_MOUNT_NOAC) != 0);

+	       (data.flags & NFS4_MOUNT_NOAC) != 0,

+	       (data.flags & NFS4_MOUNT_UNSHARED) != 0);

 	if (num_flavour > 0) {

 		int pf_cnt, i;

diff --git a/utils/mount/nfs_mount.h b/utils/mount/nfs_mount.h

index 4a061d8..50ce2a8 100644

--- a/utils/mount/nfs_mount.h

+++ b/utils/mount/nfs_mount.h

@@ -64,6 +64,7 @@ struct nfs_mount_data {

 #define NFS_MOUNT_NOACL     0x0800  /* 4 */

 #define NFS_MOUNT_SECFLAVOUR	0x2000	/* 5 */

 #define NFS_MOUNT_NORDIRPLUS	0x4000	/* 5 */

+#define NFS_MOUNT_UNSHARED	0x8000	/* 5 */

 /* security pseudoflavors */

diff --git a/utils/mount/nfsmount.c b/utils/mount/nfsmount.c

index 815064a..f21aaff 100644

--- a/utils/mount/nfsmount.c

+++ b/utils/mount/nfsmount.c

@@ -804,6 +804,10 @@ parse_options(char *old_opts, struct nfs_mount_data *data,

 				data->flags &= ~NFS_MOUNT_NORDIRPLUS;

 				if (!val)

 					data->flags |= NFS_MOUNT_NORDIRPLUS;

+			} else if (!strcmp(opt, "sharecache")) {

+				data->flags &= ~NFS_MOUNT_UNSHARED;

+				if (!val)

+					data->flags |= NFS_MOUNT_UNSHARED;

 #endif

 			} else {

 			bad_option: