9P: introduction of a new cache=mmap model.

 - Add cache=mmap option
 - Make mmap read-write while keeping it as synchronous as possible
 - Build writeback fid on mmap creation if it is writable

Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

diff --git a/fs/9p/v9fs.c b/fs/9p/v9fs.c
index 08f2e1e..14da825 100644 (file)
--- a/fs/9p/v9fs.c
+++ b/fs/9p/v9fs.c
@@ -56,7 +56,7 @@ enum {
        /* Options that take no arguments */
        Opt_nodevmap,
        /* Cache options */
-       Opt_cache_loose, Opt_fscache,
+       Opt_cache_loose, Opt_fscache, Opt_mmap,
        /* Access options */
        Opt_access, Opt_posixacl,
        /* Error token */
@@ -74,6 +74,7 @@ static const match_table_t tokens = {
        {Opt_cache, "cache=%s"},
        {Opt_cache_loose, "loose"},
        {Opt_fscache, "fscache"},
+       {Opt_mmap, "mmap"},
        {Opt_cachetag, "cachetag=%s"},
        {Opt_access, "access=%s"},
        {Opt_posixacl, "posixacl"},
@@ -91,6 +92,9 @@ static int get_cache_mode(char *s)
        } else if (!strcmp(s, "fscache")) {
                version = CACHE_FSCACHE;
                p9_debug(P9_DEBUG_9P, "Cache mode: fscache\n");
+       } else if (!strcmp(s, "mmap")) {
+               version = CACHE_MMAP;
+               p9_debug(P9_DEBUG_9P, "Cache mode: mmap\n");
        } else if (!strcmp(s, "none")) {
                version = CACHE_NONE;
                p9_debug(P9_DEBUG_9P, "Cache mode: none\n");
@@ -220,6 +224,9 @@ static int v9fs_parse_options(struct v9fs_session_info *v9ses, char *opts)
                case Opt_fscache:
                        v9ses->cache = CACHE_FSCACHE;
                        break;
+               case Opt_mmap:
+                       v9ses->cache = CACHE_MMAP;
+                       break;
                case Opt_cachetag:
 #ifdef CONFIG_9P_FSCACHE
                        v9ses->cachetag = match_strdup(&args[0]);

diff --git a/fs/9p/v9fs.h b/fs/9p/v9fs.h
index a8e127c..099c771 100644 (file)
--- a/fs/9p/v9fs.h
+++ b/fs/9p/v9fs.h
@@ -64,6 +64,7 @@ enum p9_session_flags {
 
 enum p9_cache_modes {
        CACHE_NONE,
+       CACHE_MMAP,
        CACHE_LOOSE,
        CACHE_FSCACHE,
 };

diff --git a/fs/9p/v9fs_vfs.h b/fs/9p/v9fs_vfs.h
index dc95a25..b83ebfb 100644 (file)
--- a/fs/9p/v9fs_vfs.h
+++ b/fs/9p/v9fs_vfs.h
@@ -50,6 +50,8 @@ extern const struct dentry_operations v9fs_dentry_operations;
 extern const struct dentry_operations v9fs_cached_dentry_operations;
 extern const struct file_operations v9fs_cached_file_operations;
 extern const struct file_operations v9fs_cached_file_operations_dotl;
+extern const struct file_operations v9fs_mmap_file_operations;
+extern const struct file_operations v9fs_mmap_file_operations_dotl;
 extern struct kmem_cache *v9fs_inode_cache;
 
 struct inode *v9fs_alloc_inode(struct super_block *sb);

diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
index 9ff073f..c71e886 100644 (file)
--- a/fs/9p/vfs_addr.c
+++ b/fs/9p/vfs_addr.c
@@ -202,6 +202,8 @@ static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc)
 {
        int retval;
 
+       p9_debug(P9_DEBUG_VFS, "page %p\n", page);
+
        retval = v9fs_vfs_writepage_locked(page);
        if (retval < 0) {
                if (retval == -EAGAIN) {
@@ -282,6 +284,9 @@ static int v9fs_write_begin(struct file *filp, struct address_space *mapping,
        pgoff_t index = pos >> PAGE_CACHE_SHIFT;
        struct inode *inode = mapping->host;
 
+
+       p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
+
        v9inode = V9FS_I(inode);
 start:
        page = grab_cache_page_write_begin(mapping, index, flags);
@@ -312,6 +317,8 @@ static int v9fs_write_end(struct file *filp, struct address_space *mapping,
        loff_t last_pos = pos + copied;
        struct inode *inode = page->mapping->host;
 
+       p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
+
        if (unlikely(copied < len)) {
                /*
                 * zero out the rest of the area

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 27782bb..a16b0ff 100644 (file)
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -45,6 +45,7 @@
 #include "cache.h"
 
 static const struct vm_operations_struct v9fs_file_vm_ops;
+static const struct vm_operations_struct v9fs_mmap_file_vm_ops;
 
 /**
  * v9fs_file_open - open a file (or directory)
@@ -87,7 +88,8 @@ int v9fs_file_open(struct inode *inode, struct file *file)
 
        file->private_data = fid;
        mutex_lock(&v9inode->v_mutex);
-       if (v9ses->cache && !v9inode->writeback_fid &&
+       if ((v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) &&
+           !v9inode->writeback_fid &&
            ((file->f_flags & O_ACCMODE) != O_RDONLY)) {
                /*
                 * clone a fid and add it to writeback_fid
@@ -105,7 +107,7 @@ int v9fs_file_open(struct inode *inode, struct file *file)
                v9inode->writeback_fid = (void *) fid;
        }
        mutex_unlock(&v9inode->v_mutex);
-       if (v9ses->cache)
+       if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
                v9fs_cache_inode_set_cookie(inode, file);
        return 0;
 out_error:
@@ -579,11 +581,12 @@ int v9fs_file_fsync_dotl(struct file *filp, loff_t start, loff_t end,
 }
 
 static int
-v9fs_file_mmap(struct file *file, struct vm_area_struct *vma)
+v9fs_file_mmap(struct file *filp, struct vm_area_struct *vma)
 {
        int retval;
 
-       retval = generic_file_mmap(file, vma);
+
+       retval = generic_file_mmap(filp, vma);
        if (!retval)
                vma->vm_ops = &v9fs_file_vm_ops;
 
@@ -591,6 +594,43 @@ v9fs_file_mmap(struct file *file, struct vm_area_struct *vma)
 }
 
 static int
+v9fs_mmap_file_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+       int retval;
+       struct inode *inode;
+       struct v9fs_inode *v9inode;
+       struct p9_fid *fid;
+
+       inode = file_inode(filp);
+       v9inode = V9FS_I(inode);
+       mutex_lock(&v9inode->v_mutex);
+       if (!v9inode->writeback_fid &&
+           (vma->vm_flags & VM_WRITE)) {
+               /*
+                * clone a fid and add it to writeback_fid
+                * we do it during mmap instead of
+                * page dirty time via write_begin/page_mkwrite
+                * because we want write after unlink usecase
+                * to work.
+                */
+               fid = v9fs_writeback_fid(filp->f_path.dentry);
+               if (IS_ERR(fid)) {
+                       retval = PTR_ERR(fid);
+                       mutex_unlock(&v9inode->v_mutex);
+                       return retval;
+               }
+               v9inode->writeback_fid = (void *) fid;
+       }
+       mutex_unlock(&v9inode->v_mutex);
+
+       retval = generic_file_mmap(filp, vma);
+       if (!retval)
+               vma->vm_ops = &v9fs_mmap_file_vm_ops;
+
+       return retval;
+}
+
+static int
 v9fs_vm_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
        struct v9fs_inode *v9inode;
@@ -658,6 +698,22 @@ v9fs_cached_file_read(struct file *filp, char __user *data, size_t count,
        return do_sync_read(filp, data, count, offset);
 }
 
+/**
+ * v9fs_mmap_file_read - read from a file
+ * @filp: file pointer to read
+ * @udata: user data buffer to read data into
+ * @count: size of buffer
+ * @offset: offset at which to read data
+ *
+ */
+static ssize_t
+v9fs_mmap_file_read(struct file *filp, char __user *data, size_t count,
+                     loff_t *offset)
+{
+       /* TODO: Check if there are dirty pages */
+       return v9fs_file_read(filp, data, count, offset);
+}
+
 static ssize_t
 v9fs_direct_write(struct file *filp, const char __user * data,
                  size_t count, loff_t *offsetp)
@@ -728,12 +784,65 @@ v9fs_cached_file_write(struct file *filp, const char __user * data,
        return do_sync_write(filp, data, count, offset);
 }
 
+
+/**
+ * v9fs_mmap_file_write - write to a file
+ * @filp: file pointer to write
+ * @data: data buffer to write data from
+ * @count: size of buffer
+ * @offset: offset at which to write data
+ *
+ */
+static ssize_t
+v9fs_mmap_file_write(struct file *filp, const char __user *data,
+                      size_t count, loff_t *offset)
+{
+       /*
+        * TODO: invalidate mmaps on filp's inode between
+        * offset and offset+count
+        */
+       return v9fs_file_write(filp, data, count, offset);
+}
+
+static void v9fs_mmap_vm_close(struct vm_area_struct *vma)
+{
+       struct inode *inode;
+
+       struct writeback_control wbc = {
+               .nr_to_write = LONG_MAX,
+               .sync_mode = WB_SYNC_ALL,
+               .range_start = vma->vm_pgoff * PAGE_SIZE,
+                /* absolute end, byte at end included */
+               .range_end = vma->vm_pgoff * PAGE_SIZE +
+                       (vma->vm_end - vma->vm_start - 1),
+       };
+
+
+       p9_debug(P9_DEBUG_VFS, "9p VMA close, %p, flushing", vma);
+
+       inode = file_inode(vma->vm_file);
+
+       if (!mapping_cap_writeback_dirty(inode->i_mapping))
+               wbc.nr_to_write = 0;
+
+       might_sleep();
+       sync_inode(inode, &wbc);
+}
+
+
 static const struct vm_operations_struct v9fs_file_vm_ops = {
        .fault = filemap_fault,
        .page_mkwrite = v9fs_vm_page_mkwrite,
        .remap_pages = generic_file_remap_pages,
 };
 
+static const struct vm_operations_struct v9fs_mmap_file_vm_ops = {
+       .close = v9fs_mmap_vm_close,
+       .fault = filemap_fault,
+       .page_mkwrite = v9fs_vm_page_mkwrite,
+       .remap_pages = generic_file_remap_pages,
+};
+
 
 const struct file_operations v9fs_cached_file_operations = {
        .llseek = generic_file_llseek,
@@ -784,3 +893,26 @@ const struct file_operations v9fs_file_operations_dotl = {
        .mmap = generic_file_readonly_mmap,
        .fsync = v9fs_file_fsync_dotl,
 };
+
+const struct file_operations v9fs_mmap_file_operations = {
+       .llseek = generic_file_llseek,
+       .read = v9fs_mmap_file_read,
+       .write = v9fs_mmap_file_write,
+       .open = v9fs_file_open,
+       .release = v9fs_dir_release,
+       .lock = v9fs_file_lock,
+       .mmap = v9fs_mmap_file_mmap,
+       .fsync = v9fs_file_fsync,
+};
+
+const struct file_operations v9fs_mmap_file_operations_dotl = {
+       .llseek = generic_file_llseek,
+       .read = v9fs_mmap_file_read,
+       .write = v9fs_mmap_file_write,
+       .open = v9fs_file_open,
+       .release = v9fs_dir_release,
+       .lock = v9fs_file_lock_dotl,
+       .flock = v9fs_file_flock_dotl,
+       .mmap = v9fs_mmap_file_mmap,
+       .fsync = v9fs_file_fsync_dotl,
+};

diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index af7d531..bb7991c 100644 (file)
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -299,15 +299,22 @@ int v9fs_init_inode(struct v9fs_session_info *v9ses,
        case S_IFREG:
                if (v9fs_proto_dotl(v9ses)) {
                        inode->i_op = &v9fs_file_inode_operations_dotl;
-                       if (v9ses->cache)
+                       if (v9ses->cache == CACHE_LOOSE ||
+                           v9ses->cache == CACHE_FSCACHE)
                                inode->i_fop =
                                        &v9fs_cached_file_operations_dotl;
+                       else if (v9ses->cache == CACHE_MMAP)
+                               inode->i_fop = &v9fs_mmap_file_operations_dotl;
                        else
                                inode->i_fop = &v9fs_file_operations_dotl;
                } else {
                        inode->i_op = &v9fs_file_inode_operations;
-                       if (v9ses->cache)
-                               inode->i_fop = &v9fs_cached_file_operations;
+                       if (v9ses->cache == CACHE_LOOSE ||
+                           v9ses->cache == CACHE_FSCACHE)
+                               inode->i_fop =
+                                       &v9fs_cached_file_operations;
+                       else if (v9ses->cache == CACHE_MMAP)
+                               inode->i_fop = &v9fs_mmap_file_operations;
                        else
                                inode->i_fop = &v9fs_file_operations;
                }
@@ -810,7 +817,7 @@ struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
         * unlink. For cached mode create calls request for new
         * inode. But with cache disabled, lookup should do this.
         */
-       if (v9ses->cache)
+       if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
                inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
        else
                inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
@@ -876,7 +883,8 @@ v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
        v9fs_invalidate_inode_attr(dir);
        v9inode = V9FS_I(dentry->d_inode);
        mutex_lock(&v9inode->v_mutex);
-       if (v9ses->cache && !v9inode->writeback_fid &&
+       if ((v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) &&
+           !v9inode->writeback_fid &&
            ((flags & O_ACCMODE) != O_RDONLY)) {
                /*
                 * clone a fid and add it to writeback_fid
@@ -899,7 +907,7 @@ v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
                goto error;
 
        file->private_data = fid;
-       if (v9ses->cache)
+       if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
                v9fs_cache_inode_set_cookie(dentry->d_inode, file);
 
        *opened |= FILE_CREATED;
@@ -1477,7 +1485,7 @@ int v9fs_refresh_inode(struct p9_fid *fid, struct inode *inode)
         */
        i_size = inode->i_size;
        v9fs_stat2inode(st, inode, inode->i_sb);
-       if (v9ses->cache)
+       if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
                inode->i_size = i_size;
        spin_unlock(&inode->i_lock);
 out:

diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
index 9801306..59dc8e8 100644 (file)
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -330,7 +330,8 @@ v9fs_vfs_atomic_open_dotl(struct inode *dir, struct dentry *dentry,
 
        v9inode = V9FS_I(inode);
        mutex_lock(&v9inode->v_mutex);
-       if (v9ses->cache && !v9inode->writeback_fid &&
+       if ((v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) &&
+           !v9inode->writeback_fid &&
            ((flags & O_ACCMODE) != O_RDONLY)) {
                /*
                 * clone a fid and add it to writeback_fid
@@ -353,7 +354,7 @@ v9fs_vfs_atomic_open_dotl(struct inode *dir, struct dentry *dentry,
        if (err)
                goto err_clunk_old_fid;
        file->private_data = ofid;
-       if (v9ses->cache)
+       if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
                v9fs_cache_inode_set_cookie(inode, file);
        *opened |= FILE_CREATED;
 out:
@@ -710,7 +711,7 @@ v9fs_vfs_symlink_dotl(struct inode *dir, struct dentry *dentry,
        }
 
        v9fs_invalidate_inode_attr(dir);
-       if (v9ses->cache) {
+       if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
                /* Now walk from the parent so we can get an unopened fid. */
                fid = p9_client_walk(dfid, 1, &name, 1);
                if (IS_ERR(fid)) {
@@ -965,7 +966,7 @@ int v9fs_refresh_inode_dotl(struct p9_fid *fid, struct inode *inode)
         */
        i_size = inode->i_size;
        v9fs_stat2inode_dotl(st, inode);
-       if (v9ses->cache)
+       if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
                inode->i_size = i_size;
        spin_unlock(&inode->i_lock);
 out:

diff --git a/fs/9p/vfs_super.c b/fs/9p/vfs_super.c
index 2756dcd..0afd038 100644 (file)
--- a/fs/9p/vfs_super.c
+++ b/fs/9p/vfs_super.c
@@ -144,7 +144,7 @@ static struct dentry *v9fs_mount(struct file_system_type *fs_type, int flags,
        }
        v9fs_fill_super(sb, v9ses, flags, data);
 
-       if (v9ses->cache)
+       if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
                sb->s_d_op = &v9fs_cached_dentry_operations;
        else
                sb->s_d_op = &v9fs_dentry_operations;
@@ -282,7 +282,7 @@ static int v9fs_drop_inode(struct inode *inode)
 {
        struct v9fs_session_info *v9ses;
        v9ses = v9fs_inode2v9ses(inode);
-       if (v9ses->cache)
+       if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
                return generic_drop_inode(inode);
        /*
         * in case of non cached mode always drop the
@@ -325,10 +325,12 @@ static int v9fs_write_inode_dotl(struct inode *inode,
         * send an fsync request to server irrespective of
         * wbc->sync_mode.
         */
-       p9_debug(P9_DEBUG_VFS, "%s: inode %p\n", __func__, inode);
        v9inode = V9FS_I(inode);
+       p9_debug(P9_DEBUG_VFS, "%s: inode %p, writeback_fid %p\n",
+                __func__, inode, v9inode->writeback_fid);
        if (!v9inode->writeback_fid)
                return 0;
+
        ret = p9_client_fsync(v9inode->writeback_fid, 0);
        if (ret < 0) {
                __mark_inode_dirty(inode, I_DIRTY_DATASYNC);