fs/9p: allow disable of xattr support on mount

xattr creates a lot of additional messages for 9p in
the current implementation.  This allows users to
conditionalize xattr support on 9p mount if they
are on a connection with bad latency.  Using this
flag is also useful when debugging other aspects
of 9p as it reduces the noise in the trace files.

Signed-off-by: Eric Van Hensbergen <ericvh@kernel.org>
Reviewed-by: Dominique Martinet <asmadeus@codewreck.org>

diff --git a/Documentation/filesystems/9p.rst b/Documentation/filesystems/9p.rst
index 7b5964bc88652dc604ba44392d124555493e2af0..0e800b8f73cc3a7801fcf64bd5290d01f05821c0 100644 (file)
--- a/Documentation/filesystems/9p.rst
+++ b/Documentation/filesystems/9p.rst
@@ -137,6 +137,8 @@ Options
                This can be used to share devices/named pipes/sockets between
                hosts.  This functionality will be expanded in later versions.
 
+  noxattr      do not offer xattr functions on this mount.
+
   access       there are four access modes.
                        user
                                if a user tries to access a file on v9fs

diff --git a/fs/9p/v9fs.c b/fs/9p/v9fs.c
index a46bf9121f11a8c9f5861091095ee58936227dd9..f8e952c013f905efd96564a188ac4b67ed9d2b72 100644 (file)
--- a/fs/9p/v9fs.c
+++ b/fs/9p/v9fs.c
@@ -38,7 +38,7 @@ enum {
        /* String options */
        Opt_uname, Opt_remotename, Opt_cache, Opt_cachetag,
        /* Options that take no arguments */
-       Opt_nodevmap,
+       Opt_nodevmap, Opt_noxattr,
        /* Access options */
        Opt_access, Opt_posixacl,
        /* Lock timeout option */
@@ -55,6 +55,7 @@ static const match_table_t tokens = {
        {Opt_uname, "uname=%s"},
        {Opt_remotename, "aname=%s"},
        {Opt_nodevmap, "nodevmap"},
+       {Opt_noxattr, "noxattr"},
        {Opt_cache, "cache=%s"},
        {Opt_cachetag, "cachetag=%s"},
        {Opt_access, "access=%s"},
@@ -149,6 +150,9 @@ int v9fs_show_options(struct seq_file *m, struct dentry *root)
        if (v9ses->flags & V9FS_POSIX_ACL)
                seq_puts(m, ",posixacl");
 
+       if (v9ses->flags & V9FS_NO_XATTR)
+               seq_puts(m, ",noxattr");
+
        return p9_show_client_options(m, v9ses->clnt);
 }
 
@@ -269,6 +273,9 @@ static int v9fs_parse_options(struct v9fs_session_info *v9ses, char *opts)
                case Opt_nodevmap:
                        v9ses->nodev = 1;
                        break;
+               case Opt_noxattr:
+                       v9ses->flags |= V9FS_NO_XATTR;
+                       break;
                case Opt_cachetag:
 #ifdef CONFIG_9P_FSCACHE
                        kfree(v9ses->cachetag);

diff --git a/fs/9p/v9fs.h b/fs/9p/v9fs.h
index e5d41804b3cd1cb4ad9257262259b63a6927fb55..8cd63782a25c182fa9e18f29f922b0cf30fe6974 100644 (file)
--- a/fs/9p/v9fs.h
+++ b/fs/9p/v9fs.h
@@ -36,7 +36,8 @@ enum p9_session_flags {
        V9FS_ACCESS_SINGLE      = 0x04,
        V9FS_ACCESS_USER        = 0x08,
        V9FS_ACCESS_CLIENT      = 0x10,
-       V9FS_POSIX_ACL          = 0x20
+       V9FS_POSIX_ACL          = 0x20,
+       V9FS_NO_XATTR           = 0x40
 };
 
 /* possible values of ->cache */

diff --git a/fs/9p/vfs_super.c b/fs/9p/vfs_super.c
index 65d96fa94ba228327c6f517a65bb50af64c5af72..5fc6a945bfff49df45cb31c1f15ad5e859fa2556 100644 (file)
--- a/fs/9p/vfs_super.c
+++ b/fs/9p/vfs_super.c
@@ -64,7 +64,8 @@ v9fs_fill_super(struct super_block *sb, struct v9fs_session_info *v9ses,
        sb->s_magic = V9FS_MAGIC;
        if (v9fs_proto_dotl(v9ses)) {
                sb->s_op = &v9fs_super_ops_dotl;
-               sb->s_xattr = v9fs_xattr_handlers;
+               if (!(v9ses->flags & V9FS_NO_XATTR))
+                       sb->s_xattr = v9fs_xattr_handlers;
        } else {
                sb->s_op = &v9fs_super_ops;
                sb->s_time_max = U32_MAX;