Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e03abc0c963a31cb07dfbc07c7d85d75e0d13cf4
Commit:     e03abc0c963a31cb07dfbc07c7d85d75e0d13cf4
Parent:     2c0463a9ae8751547c39302aeb31c6cef16b5df4
Author:     Eric Van Hensbergen <[EMAIL PROTECTED]>
AuthorDate: Sun Feb 11 13:21:39 2007 -0600
Committer:  Eric Van Hensbergen <[EMAIL PROTECTED]>
CommitDate: Sun Feb 18 10:16:10 2007 -0600

    9p: implement optional loose read cache
    
    While cacheing is generally frowned upon in the 9p world, it has its
    place -- particularly in situations where the remote file system is
    exclusive and/or read-only.  The vacfs views of venti content addressable
    store are a real-world instance of such a situation.  To facilitate higher
    performance for these workloads (and eventually use the fscache patches),
    we have enabled a "loose" cache mode which does not attempt to maintain
    any form of consistency on the page-cache or dcache.  This results in over
    two orders of magnitude performance improvement for cacheable block reads
    in the Bonnie benchmark.  The more aggressive use of the dcache also seems
    to improve metadata operational performance.
    
    Signed-off-by: Eric Van Hensbergen <[EMAIL PROTECTED]>
---
 Documentation/filesystems/00-INDEX |    4 ++--
 Documentation/filesystems/9p.txt   |    4 ++++
 fs/9p/fid.c                        |    3 ++-
 fs/9p/v9fs.c                       |    9 ++++++++-
 fs/9p/v9fs.h                       |    9 ++++++++-
 fs/9p/v9fs_vfs.h                   |    2 ++
 fs/9p/vfs_addr.c                   |    2 ++
 fs/9p/vfs_dentry.c                 |   26 ++++++++++++++++++++++++++
 fs/9p/vfs_file.c                   |   18 ++++++++++++++++++
 fs/9p/vfs_inode.c                  |   20 ++++++++++++++++----
 10 files changed, 88 insertions(+), 9 deletions(-)

diff --git a/Documentation/filesystems/00-INDEX 
b/Documentation/filesystems/00-INDEX
index 4dc28cc..5717858 100644
--- a/Documentation/filesystems/00-INDEX
+++ b/Documentation/filesystems/00-INDEX
@@ -4,6 +4,8 @@ Exporting
        - explanation of how to make filesystems exportable.
 Locking
        - info on locking rules as they pertain to Linux VFS.
+9p.txt
+       - 9p (v9fs) is an implementation of the Plan 9 remote fs protocol.
 adfs.txt
        - info and mount options for the Acorn Advanced Disc Filing System.
 afs.txt
@@ -82,8 +84,6 @@ udf.txt
        - info and mount options for the UDF filesystem.
 ufs.txt
        - info on the ufs filesystem.
-v9fs.txt
-       - v9fs is a Unix implementation of the Plan 9 9p remote fs protocol.
 vfat.txt
        - info on using the VFAT filesystem used in Windows NT and Windows 95
 vfs.txt
diff --git a/Documentation/filesystems/9p.txt b/Documentation/filesystems/9p.txt
index 4d075a4..bbd8b28 100644
--- a/Documentation/filesystems/9p.txt
+++ b/Documentation/filesystems/9p.txt
@@ -40,6 +40,10 @@ OPTIONS
   aname=name   aname specifies the file tree to access when the server is
                offering several exported file systems.
 
+  cache=mode   specifies a cacheing policy.  By default, no caches are used.
+                       loose = no attempts are made at consistency,
+                                intended for exclusive, read-only mounts
+
   debug=n      specifies debug level.  The debug level is a bitmask.
                        0x01 = display verbose error messages
                        0x02 = developer debug (DEBUG_CURRENT)
diff --git a/fs/9p/fid.c b/fs/9p/fid.c
index a9b6301..9041971 100644
--- a/fs/9p/fid.c
+++ b/fs/9p/fid.c
@@ -136,7 +136,8 @@ struct v9fs_fid *v9fs_fid_lookup(struct dentry *dentry)
 }
 
 /**
- * v9fs_fid_clone - lookup the fid for a dentry, clone a private copy and 
release it
+ * v9fs_fid_clone - lookup the fid for a dentry, clone a private copy and
+ *                     release it
  * @dentry: dentry to look for fid in
  *
  * find a fid in the dentry and then clone to a new private fid
diff --git a/fs/9p/v9fs.c b/fs/9p/v9fs.c
index d9b561b..6ad6f19 100644
--- a/fs/9p/v9fs.c
+++ b/fs/9p/v9fs.c
@@ -53,6 +53,8 @@ enum {
        Opt_uname, Opt_remotename,
        /* Options that take no arguments */
        Opt_legacy, Opt_nodevmap, Opt_unix, Opt_tcp, Opt_fd,
+       /* Cache options */
+       Opt_cache_loose,
        /* Error token */
        Opt_err
 };
@@ -76,6 +78,8 @@ static match_table_t tokens = {
        {Opt_fd, "fd"},
        {Opt_legacy, "noextend"},
        {Opt_nodevmap, "nodevmap"},
+       {Opt_cache_loose, "cache=loose"},
+       {Opt_cache_loose, "loose"},
        {Opt_err, NULL}
 };
 
@@ -106,6 +110,7 @@ static void v9fs_parse_options(char *options, struct 
v9fs_session_info *v9ses)
        v9ses->debug = 0;
        v9ses->rfdno = ~0;
        v9ses->wfdno = ~0;
+       v9ses->cache = 0;
 
        if (!options)
                return;
@@ -121,7 +126,6 @@ static void v9fs_parse_options(char *options, struct 
v9fs_session_info *v9ses)
                                        "integer field, but no integer?\n");
                                continue;
                        }
-
                }
                switch (token) {
                case Opt_port:
@@ -169,6 +173,9 @@ static void v9fs_parse_options(char *options, struct 
v9fs_session_info *v9ses)
                case Opt_nodevmap:
                        v9ses->nodev = 1;
                        break;
+               case Opt_cache_loose:
+                       v9ses->cache = CACHE_LOOSE;
+                       break;
                default:
                        continue;
                }
diff --git a/fs/9p/v9fs.h b/fs/9p/v9fs.h
index c134d10..820bf5c 100644
--- a/fs/9p/v9fs.h
+++ b/fs/9p/v9fs.h
@@ -47,7 +47,7 @@ struct v9fs_session_info {
        unsigned int afid;      /* authentication fid */
        unsigned int rfdno;     /* read file descriptor number */
        unsigned int wfdno;     /* write file descriptor number */
-
+       unsigned int cache;     /* cache mode */
 
        char *name;             /* user name to mount as */
        char *remotename;       /* name of remote hierarchy being mounted */
@@ -73,6 +73,13 @@ enum {
        PROTO_FD,
 };
 
+/* possible values of ->cache */
+/* eventually support loose, tight, time, session, default always none */
+enum {
+       CACHE_NONE,             /* default */
+       CACHE_LOOSE,            /* no consistency */
+};
+
 extern struct dentry *v9fs_debugfs_root;
 
 int v9fs_session_init(struct v9fs_session_info *, const char *, char *);
diff --git a/fs/9p/v9fs_vfs.h b/fs/9p/v9fs_vfs.h
index 450b0c1..8ada4c5 100644
--- a/fs/9p/v9fs_vfs.h
+++ b/fs/9p/v9fs_vfs.h
@@ -40,8 +40,10 @@
 extern struct file_system_type v9fs_fs_type;
 extern const struct address_space_operations v9fs_addr_operations;
 extern const struct file_operations v9fs_file_operations;
+extern const struct file_operations v9fs_cached_file_operations;
 extern const struct file_operations v9fs_dir_operations;
 extern struct dentry_operations v9fs_dentry_operations;
+extern struct dentry_operations v9fs_cached_dentry_operations;
 
 struct inode *v9fs_get_inode(struct super_block *sb, int mode);
 ino_t v9fs_qid2ino(struct v9fs_qid *qid);
diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
index cc24abf..bed48fa 100644
--- a/fs/9p/vfs_addr.c
+++ b/fs/9p/vfs_addr.c
@@ -63,6 +63,8 @@ static int v9fs_vfs_readpage(struct file *filp, struct page 
*page)
        int total = 0;
        int result = 0;
 
+       dprintk(DEBUG_VFS, "\n");
+
        buffer = kmap(page);
        do {
                if (count < rsize)
diff --git a/fs/9p/vfs_dentry.c b/fs/9p/vfs_dentry.c
index 062daa6..ddffd8a 100644
--- a/fs/9p/vfs_dentry.c
+++ b/fs/9p/vfs_dentry.c
@@ -53,10 +53,31 @@
 static int v9fs_dentry_delete(struct dentry *dentry)
 {
        dprintk(DEBUG_VFS, " dentry: %s (%p)\n", dentry->d_iname, dentry);
+
        return 1;
 }
 
 /**
+ * v9fs_cached_dentry_delete - called when dentry refcount equals 0
+ * @dentry:  dentry in question
+ *
+ * Only return 1 if our inode is invalid.  Only non-synthetic files
+ * (ones without mtime == 0) should be calling this function.
+ *
+ */
+
+static int v9fs_cached_dentry_delete(struct dentry *dentry)
+{
+       struct inode *inode = dentry->d_inode;
+       dprintk(DEBUG_VFS, " dentry: %s (%p)\n", dentry->d_iname, dentry);
+
+       if(!inode)
+               return 1;
+
+       return 0;
+}
+
+/**
  * v9fs_dentry_release - called when dentry is going to be freed
  * @dentry:  dentry that is being release
  *
@@ -87,6 +108,11 @@ void v9fs_dentry_release(struct dentry *dentry)
        }
 }
 
+struct dentry_operations v9fs_cached_dentry_operations = {
+       .d_delete = v9fs_cached_dentry_delete,
+       .d_release = v9fs_dentry_release,
+};
+
 struct dentry_operations v9fs_dentry_operations = {
        .d_delete = v9fs_dentry_delete,
        .d_release = v9fs_dentry_release,
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 6c78343..653dfa5 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -79,6 +79,13 @@ int v9fs_file_open(struct inode *inode, struct file *file)
        vfid->filp = file;
        kfree(fcall);
 
+       if((vfid->qid.version) && (v9ses->cache)) {
+               dprintk(DEBUG_VFS, "cached");
+               /* enable cached file options */
+               if(file->f_op == &v9fs_file_operations)
+                       file->f_op = &v9fs_cached_file_operations;
+       }
+
        return 0;
 
 Clunk_Fid:
@@ -238,6 +245,17 @@ v9fs_file_write(struct file *filp, const char __user * 
data,
        return total;
 }
 
+const struct file_operations v9fs_cached_file_operations = {
+       .llseek = generic_file_llseek,
+       .read = do_sync_read,
+       .aio_read = generic_file_aio_read,
+       .write = v9fs_file_write,
+       .open = v9fs_file_open,
+       .release = v9fs_dir_release,
+       .lock = v9fs_file_lock,
+       .mmap = generic_file_mmap,
+};
+
 const struct file_operations v9fs_file_operations = {
        .llseek = generic_file_llseek,
        .read = v9fs_file_read,
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 5cf2213..124a085 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -504,7 +504,10 @@ v9fs_vfs_create(struct inode *dir, struct dentry *dentry, 
int mode,
                goto error;
        }
 
-       dentry->d_op = &v9fs_dentry_operations;
+       if(v9ses->cache)
+               dentry->d_op = &v9fs_cached_dentry_operations;
+       else
+               dentry->d_op = &v9fs_dentry_operations;
        d_instantiate(dentry, inode);
 
        if (nd && nd->flags & LOOKUP_OPEN) {
@@ -589,7 +592,10 @@ static int v9fs_vfs_mkdir(struct inode *dir, struct dentry 
*dentry, int mode)
                goto error;
        }
 
-       dentry->d_op = &v9fs_dentry_operations;
+       if(v9ses->cache)
+               dentry->d_op = &v9fs_cached_dentry_operations;
+       else
+               dentry->d_op = &v9fs_dentry_operations;
        d_instantiate(dentry, inode);
        return 0;
 
@@ -626,7 +632,6 @@ static struct dentry *v9fs_vfs_lookup(struct inode *dir, 
struct dentry *dentry,
 
        sb = dir->i_sb;
        v9ses = v9fs_inode2v9ses(dir);
-       dentry->d_op = &v9fs_dentry_operations;
        dirfid = v9fs_fid_lookup(dentry->d_parent);
 
        if(IS_ERR(dirfid))
@@ -697,6 +702,10 @@ static struct dentry *v9fs_vfs_lookup(struct inode *dir, 
struct dentry *dentry,
 
        fid->qid = fcall->params.rstat.stat.qid;
        v9fs_stat2inode(&fcall->params.rstat.stat, inode, inode->i_sb);
+       if((fid->qid.version)&&(v9ses->cache))
+               dentry->d_op = &v9fs_cached_dentry_operations;
+       else
+               dentry->d_op = &v9fs_dentry_operations;
 
        d_add(dentry, inode);
        kfree(fcall);
@@ -1184,7 +1193,10 @@ static int v9fs_vfs_mkspecial(struct inode *dir, struct 
dentry *dentry,
                goto free_vfid;
        }
 
-       dentry->d_op = &v9fs_dentry_operations;
+       if(v9ses->cache)
+               dentry->d_op = &v9fs_cached_dentry_operations;
+       else
+               dentry->d_op = &v9fs_dentry_operations;
        d_instantiate(dentry, inode);
        return 0;
 
-
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