[PATCH] FUSE - readpages operation

This patch adds readpages support to FUSE.

With the help of the readpages() operation multiple reads are bundled
together and sent as a single request to userspace.  This can improve
reading performace.

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 85 insertions, 0 deletions

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 96ea302db184..86ffb6db5fe7 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -227,6 +227,72 @@ static int fuse_readpage(struct file *file, struct page *page)
         return err;
 }
 
+static int fuse_send_readpages(struct fuse_req *req, struct file *file,
+                               struct inode *inode)
+{
+        loff_t pos = (loff_t) req->pages[0]->index << PAGE_CACHE_SHIFT;
+        size_t count = req->num_pages << PAGE_CACHE_SHIFT;
+        unsigned i;
+        req->out.page_zeroing = 1;
+        fuse_send_read(req, file, inode, pos, count);
+        for (i = 0; i < req->num_pages; i++) {
+                struct page *page = req->pages[i];
+                if (!req->out.h.error)
+                        SetPageUptodate(page);
+                unlock_page(page);
+        }
+        return req->out.h.error;
+}
+
+struct fuse_readpages_data {
+        struct fuse_req *req;
+        struct file *file;
+        struct inode *inode;
+};
+
+static int fuse_readpages_fill(void *_data, struct page *page)
+{
+        struct fuse_readpages_data *data = _data;
+        struct fuse_req *req = data->req;
+        struct inode *inode = data->inode;
+        struct fuse_conn *fc = get_fuse_conn(inode);
+
+        if (req->num_pages &&
+            (req->num_pages == FUSE_MAX_PAGES_PER_REQ ||
+             (req->num_pages + 1) * PAGE_CACHE_SIZE > fc->max_read ||
+             req->pages[req->num_pages - 1]->index + 1 != page->index)) {
+                int err = fuse_send_readpages(req, data->file, inode);
+                if (err) {
+                        unlock_page(page);
+                        return err;
+                }
+                fuse_reset_request(req);
+        }
+        req->pages[req->num_pages] = page;
+        req->num_pages ++;
+        return 0;
+}
+
+static int fuse_readpages(struct file *file, struct address_space *mapping,
+                          struct list_head *pages, unsigned nr_pages)
+{
+        struct inode *inode = mapping->host;
+        struct fuse_conn *fc = get_fuse_conn(inode);
+        struct fuse_readpages_data data;
+        int err;
+        data.file = file;
+        data.inode = inode;
+        data.req = fuse_get_request_nonint(fc);
+        if (!data.req)
+                return -EINTR;
+
+        err = read_cache_pages(mapping, pages, fuse_readpages_fill, &data);
+        if (!err && data.req->num_pages)
+                err = fuse_send_readpages(data.req, file, inode);
+        fuse_put_request(fc, data.req);
+        return err;
+}
+
 static ssize_t fuse_send_write(struct fuse_req *req, struct file *file,
                                struct inode *inode, loff_t pos, size_t count)
 {
@@ -331,6 +397,7 @@ static struct address_space_operations fuse_file_aops  = {
         .readpage       = fuse_readpage,
         .prepare_write  = fuse_prepare_write,
         .commit_write   = fuse_commit_write,
+        .readpages      = fuse_readpages,
         .set_page_dirty = fuse_set_page_dirty,
 };
 
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 86183c562104..aff3a01ea02b 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -201,6 +201,9 @@ struct fuse_conn {
         /** The fuse mount flags for this mount */
         unsigned flags;
 
+        /** Maximum read size */
+        unsigned max_read;
+
         /** Readers of the connection are waiting on this */
         wait_queue_head_t waitq;
 
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 458c62ca0fec..0b75c73386e9 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -32,6 +32,7 @@ struct fuse_mount_data {
         unsigned rootmode;
         unsigned user_id;
         unsigned flags;
+        unsigned max_read;
 };
 
 static struct inode *fuse_alloc_inode(struct super_block *sb)
@@ -250,6 +251,7 @@ enum {
         OPT_DEFAULT_PERMISSIONS,
         OPT_ALLOW_OTHER,
         OPT_KERNEL_CACHE,
+        OPT_MAX_READ,
         OPT_ERR
 };
 
@@ -260,6 +262,7 @@ static match_table_t tokens = {
         {OPT_DEFAULT_PERMISSIONS,       "default_permissions"},
         {OPT_ALLOW_OTHER,               "allow_other"},
         {OPT_KERNEL_CACHE,              "kernel_cache"},
+        {OPT_MAX_READ,                  "max_read=%u"},
         {OPT_ERR,                       NULL}
 };
 
@@ -268,6 +271,7 @@ static int parse_fuse_opt(char *opt, struct fuse_mount_data *d)
         char *p;
         memset(d, 0, sizeof(struct fuse_mount_data));
         d->fd = -1;
+        d->max_read = ~0;
 
         while ((p = strsep(&opt, ",")) != NULL) {
                 int token;
@@ -308,6 +312,12 @@ static int parse_fuse_opt(char *opt, struct fuse_mount_data *d)
                         d->flags |= FUSE_KERNEL_CACHE;
                         break;
 
+                case OPT_MAX_READ:
+                        if (match_int(&args[0], &value))
+                                return 0;
+                        d->max_read = value;
+                        break;
+
                 default:
                         return 0;
                 }
@@ -329,6 +339,8 @@ static int fuse_show_options(struct seq_file *m, struct vfsmount *mnt)
                 seq_puts(m, ",allow_other");
         if (fc->flags & FUSE_KERNEL_CACHE)
                 seq_puts(m, ",kernel_cache");
+        if (fc->max_read != ~0)
+                seq_printf(m, ",max_read=%u", fc->max_read);
         return 0;
 }
 
@@ -453,6 +465,9 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent)
 
         fc->flags = d.flags;
         fc->user_id = d.user_id;
+        fc->max_read = d.max_read;
+        if (fc->max_read / PAGE_CACHE_SIZE < fc->bdi.ra_pages)
+                fc->bdi.ra_pages = fc->max_read / PAGE_CACHE_SIZE;
 
         err = -ENOMEM;
         root = get_root_inode(sb, d.rootmode);