3 files changed, 146 insertions, 2 deletions

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 86ffb6db5fe7..6bc3fb26de39 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -363,6 +363,118 @@ static int fuse_commit_write(struct file *file, struct page *page,
         return err;
 }
 
+static void fuse_release_user_pages(struct fuse_req *req, int write)
+{
+        unsigned i;
+
+        for (i = 0; i < req->num_pages; i++) {
+                struct page *page = req->pages[i];
+                if (write)
+                        set_page_dirty_lock(page);
+                put_page(page);
+        }
+}
+
+static int fuse_get_user_pages(struct fuse_req *req, const char __user *buf,
+                               unsigned nbytes, int write)
+{
+        unsigned long user_addr = (unsigned long) buf;
+        unsigned offset = user_addr & ~PAGE_MASK;
+        int npages;
+
+        /* This doesn't work with nfsd */
+        if (!current->mm)
+                return -EPERM;
+
+        nbytes = min(nbytes, (unsigned) FUSE_MAX_PAGES_PER_REQ << PAGE_SHIFT);
+        npages = (nbytes + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
+        npages = min(npages, FUSE_MAX_PAGES_PER_REQ);
+        down_read(&current->mm->mmap_sem);
+        npages = get_user_pages(current, current->mm, user_addr, npages, write,
+                                0, req->pages, NULL);
+        up_read(&current->mm->mmap_sem);
+        if (npages < 0)
+                return npages;
+
+        req->num_pages = npages;
+        req->page_offset = offset;
+        return 0;
+}
+
+static ssize_t fuse_direct_io(struct file *file, const char __user *buf,
+                              size_t count, loff_t *ppos, int write)
+{
+        struct inode *inode = file->f_dentry->d_inode;
+        struct fuse_conn *fc = get_fuse_conn(inode);
+        size_t nmax = write ? fc->max_write : fc->max_read;
+        loff_t pos = *ppos;
+        ssize_t res = 0;
+        struct fuse_req *req = fuse_get_request(fc);
+        if (!req)
+                return -ERESTARTSYS;
+
+        while (count) {
+                size_t tmp;
+                size_t nres;
+                size_t nbytes = min(count, nmax);
+                int err = fuse_get_user_pages(req, buf, nbytes, !write);
+                if (err) {
+                        res = err;
+                        break;
+                }
+                tmp = (req->num_pages << PAGE_SHIFT) - req->page_offset;
+                nbytes = min(nbytes, tmp);
+                if (write)
+                        nres = fuse_send_write(req, file, inode, pos, nbytes);
+                else
+                        nres = fuse_send_read(req, file, inode, pos, nbytes);
+                fuse_release_user_pages(req, !write);
+                if (req->out.h.error) {
+                        if (!res)
+                                res = req->out.h.error;
+                        break;
+                } else if (nres > nbytes) {
+                        res = -EIO;
+                        break;
+                }
+                count -= nres;
+                res += nres;
+                pos += nres;
+                buf += nres;
+                if (nres != nbytes)
+                        break;
+                if (count)
+                        fuse_reset_request(req);
+        }
+        fuse_put_request(fc, req);
+        if (res > 0) {
+                if (write && pos > i_size_read(inode))
+                        i_size_write(inode, pos);
+                *ppos = pos;
+        } else if (write && (res == -EINTR || res == -EIO))
+                fuse_invalidate_attr(inode);
+
+        return res;
+}
+
+static ssize_t fuse_direct_read(struct file *file, char __user *buf,
+                                     size_t count, loff_t *ppos)
+{
+        return fuse_direct_io(file, buf, count, ppos, 0);
+}
+
+static ssize_t fuse_direct_write(struct file *file, const char __user *buf,
+                                 size_t count, loff_t *ppos)
+{
+        struct inode *inode = file->f_dentry->d_inode;
+        ssize_t res;
+        /* Don't allow parallel writes to the same file */
+        down(&inode->i_sem);
+        res = fuse_direct_io(file, buf, count, ppos, 1);
+        up(&inode->i_sem);
+        return res;
+}
+
 static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
 {
         if ((vma->vm_flags & VM_SHARED)) {
@@ -393,6 +505,17 @@ static struct file_operations fuse_file_operations = {
         .sendfile       = generic_file_sendfile,
 };
 
+static struct file_operations fuse_direct_io_file_operations = {
+        .llseek         = generic_file_llseek,
+        .read           = fuse_direct_read,
+        .write          = fuse_direct_write,
+        .open           = fuse_open,
+        .flush          = fuse_flush,
+        .release        = fuse_release,
+        .fsync          = fuse_fsync,
+        /* no mmap and sendfile */
+};
+
 static struct address_space_operations fuse_file_aops  = {
         .readpage       = fuse_readpage,
         .prepare_write  = fuse_prepare_write,
@@ -403,6 +526,12 @@ static struct address_space_operations fuse_file_aops  = {
 
 void fuse_init_file_inode(struct inode *inode)
 {
-        inode->i_fop = &fuse_file_operations;
-        inode->i_data.a_ops = &fuse_file_aops;
+        struct fuse_conn *fc = get_fuse_conn(inode);
+
+        if (fc->flags & FUSE_DIRECT_IO)
+                inode->i_fop = &fuse_direct_io_file_operations;
+        else {
+                inode->i_fop = &fuse_file_operations;
+                inode->i_data.a_ops = &fuse_file_aops;
+        }
 }
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 3ec2aff3fdb5..0af1ac646927 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -34,6 +34,9 @@
     be flushed on open */
 #define FUSE_KERNEL_CACHE        (1 << 2)
 
+/** Bypass the page cache for read and write operations  */
+#define FUSE_DIRECT_IO           (1 << 3)
+
 /** FUSE inode */
 struct fuse_inode {
         /** Inode data */
@@ -207,6 +210,9 @@ struct fuse_conn {
         /** Maximum read size */
         unsigned max_read;
 
+        /** Maximum write size */
+        unsigned max_write;
+
         /** 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 298c1d4c1534..652c9d5df973 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -258,6 +258,7 @@ enum {
         OPT_DEFAULT_PERMISSIONS,
         OPT_ALLOW_OTHER,
         OPT_KERNEL_CACHE,
+        OPT_DIRECT_IO,
         OPT_MAX_READ,
         OPT_ERR
 };
@@ -270,6 +271,7 @@ static match_table_t tokens = {
         {OPT_DEFAULT_PERMISSIONS,       "default_permissions"},
         {OPT_ALLOW_OTHER,               "allow_other"},
         {OPT_KERNEL_CACHE,              "kernel_cache"},
+        {OPT_DIRECT_IO,                 "direct_io"},
         {OPT_MAX_READ,                  "max_read=%u"},
         {OPT_ERR,                       NULL}
 };
@@ -329,6 +331,10 @@ static int parse_fuse_opt(char *opt, struct fuse_mount_data *d)
                         d->flags |= FUSE_KERNEL_CACHE;
                         break;
 
+                case OPT_DIRECT_IO:
+                        d->flags |= FUSE_DIRECT_IO;
+                        break;
+
                 case OPT_MAX_READ:
                         if (match_int(&args[0], &value))
                                 return 0;
@@ -359,6 +365,8 @@ 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->flags & FUSE_DIRECT_IO)
+                seq_puts(m, ",direct_io");
         if (fc->max_read != ~0)
                 seq_printf(m, ",max_read=%u", fc->max_read);
         return 0;
@@ -489,6 +497,7 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent)
         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;
+        fc->max_write = FUSE_MAX_IN / 2;
 
         err = -ENOMEM;
         root = get_root_inode(sb, d.rootmode);