mount.nfs: Add the mount option "nosharecache"

[nfs-utils.git] / utils / mount / nfs.man

diff --git a/utils/mount/nfs.man b/utils/mount/nfs.man
index 673556ca6c37a6b6baf33b1200645a08c1240ada..e66daba57886bd7ff31a9abe3ee7aa57f0cd8d77 100644 (file)
--- 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.
 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
 .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.
 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
 .P
 All of the non-value options have corresponding nooption forms.
 For example, nointr means don't allow file operations to be