[PATCH] FUSE - file operations

This patch adds the file operations of FUSE.

The following operations are added:

 o open
 o flush
 o release
 o fsync
 o readpage
 o commit_write

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

1 files changed, 341 insertions, 0 deletions

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
new file mode 100644
index 000000000000..de8c9c702461
--- /dev/null
+++ b/fs/fuse/file.c
@@ -0,0 +1,341 @@
+/*
+  FUSE: Filesystem in Userspace
+  Copyright (C) 2001-2005  Miklos Szeredi <miklos@szeredi.hu>
+
+  This program can be distributed under the terms of the GNU GPL.
+  See the file COPYING.
+*/
+
+#include "fuse_i.h"
+
+#include <linux/pagemap.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+
+static int fuse_open(struct inode *inode, struct file *file)
+{
+        struct fuse_conn *fc = get_fuse_conn(inode);
+        struct fuse_req *req;
+        struct fuse_open_in inarg;
+        struct fuse_open_out outarg;
+        struct fuse_file *ff;
+        int err;
+        /* Restarting the syscall is not allowed if O_CREAT and O_EXCL
+           are both set, because creation will fail on the restart */
+        int excl = (file->f_flags & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL);
+
+        err = generic_file_open(inode, file);
+        if (err)
+                return err;
+
+        /* If opening the root node, no lookup has been performed on
+           it, so the attributes must be refreshed */
+        if (get_node_id(inode) == FUSE_ROOT_ID) {
+                int err = fuse_do_getattr(inode);
+                if (err)
+                        return err;
+        }
+
+        if (excl)
+                req = fuse_get_request_nonint(fc);
+        else
+                req = fuse_get_request(fc);
+        if (!req)
+                return excl ? -EINTR : -ERESTARTSYS;
+
+        err = -ENOMEM;
+        ff = kmalloc(sizeof(struct fuse_file), GFP_KERNEL);
+        if (!ff)
+                goto out_put_request;
+
+        ff->release_req = fuse_request_alloc();
+        if (!ff->release_req) {
+                kfree(ff);
+                goto out_put_request;
+        }
+
+        memset(&inarg, 0, sizeof(inarg));
+        inarg.flags = file->f_flags & ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
+        req->in.h.opcode = FUSE_OPEN;
+        req->in.h.nodeid = get_node_id(inode);
+        req->inode = inode;
+        req->in.numargs = 1;
+        req->in.args[0].size = sizeof(inarg);
+        req->in.args[0].value = &inarg;
+        req->out.numargs = 1;
+        req->out.args[0].size = sizeof(outarg);
+        req->out.args[0].value = &outarg;
+        if (excl)
+                request_send_nonint(fc, req);
+        else
+                request_send(fc, req);
+        err = req->out.h.error;
+        if (!err)
+                invalidate_inode_pages(inode->i_mapping);
+        if (err) {
+                fuse_request_free(ff->release_req);
+                kfree(ff);
+        } else {
+                ff->fh = outarg.fh;
+                file->private_data = ff;
+        }
+
+ out_put_request:
+        fuse_put_request(fc, req);
+        return err;
+}
+
+static int fuse_release(struct inode *inode, struct file *file)
+{
+        struct fuse_conn *fc = get_fuse_conn(inode);
+        struct fuse_file *ff = file->private_data;
+        struct fuse_req *req = ff->release_req;
+        struct fuse_release_in *inarg = &req->misc.release_in;
+
+        inarg->fh = ff->fh;
+        inarg->flags = file->f_flags & ~O_EXCL;
+        req->in.h.opcode = FUSE_RELEASE;
+        req->in.h.nodeid = get_node_id(inode);
+        req->inode = inode;
+        req->in.numargs = 1;
+        req->in.args[0].size = sizeof(struct fuse_release_in);
+        req->in.args[0].value = inarg;
+        request_send_background(fc, req);
+        kfree(ff);
+
+        /* Return value is ignored by VFS */
+        return 0;
+}
+
+static int fuse_flush(struct file *file)
+{
+        struct inode *inode = file->f_dentry->d_inode;
+        struct fuse_conn *fc = get_fuse_conn(inode);
+        struct fuse_file *ff = file->private_data;
+        struct fuse_req *req;
+        struct fuse_flush_in inarg;
+        int err;
+
+        if (fc->no_flush)
+                return 0;
+
+        req = fuse_get_request_nonint(fc);
+        if (!req)
+                return -EINTR;
+
+        memset(&inarg, 0, sizeof(inarg));
+        inarg.fh = ff->fh;
+        req->in.h.opcode = FUSE_FLUSH;
+        req->in.h.nodeid = get_node_id(inode);
+        req->inode = inode;
+        req->file = file;
+        req->in.numargs = 1;
+        req->in.args[0].size = sizeof(inarg);
+        req->in.args[0].value = &inarg;
+        request_send_nonint(fc, req);
+        err = req->out.h.error;
+        fuse_put_request(fc, req);
+        if (err == -ENOSYS) {
+                fc->no_flush = 1;
+                err = 0;
+        }
+        return err;
+}
+
+static int fuse_fsync(struct file *file, struct dentry *de, int datasync)
+{
+        struct inode *inode = de->d_inode;
+        struct fuse_conn *fc = get_fuse_conn(inode);
+        struct fuse_file *ff = file->private_data;
+        struct fuse_req *req;
+        struct fuse_fsync_in inarg;
+        int err;
+
+        if (fc->no_fsync)
+                return 0;
+
+        req = fuse_get_request(fc);
+        if (!req)
+                return -ERESTARTSYS;
+
+        memset(&inarg, 0, sizeof(inarg));
+        inarg.fh = ff->fh;
+        inarg.fsync_flags = datasync ? 1 : 0;
+        req->in.h.opcode = FUSE_FSYNC;
+        req->in.h.nodeid = get_node_id(inode);
+        req->inode = inode;
+        req->file = file;
+        req->in.numargs = 1;
+        req->in.args[0].size = sizeof(inarg);
+        req->in.args[0].value = &inarg;
+        request_send(fc, req);
+        err = req->out.h.error;
+        fuse_put_request(fc, req);
+        if (err == -ENOSYS) {
+                fc->no_fsync = 1;
+                err = 0;
+        }
+        return err;
+}
+
+static ssize_t fuse_send_read(struct fuse_req *req, struct file *file,
+                              struct inode *inode, loff_t pos,  size_t count)
+{
+        struct fuse_conn *fc = get_fuse_conn(inode);
+        struct fuse_file *ff = file->private_data;
+        struct fuse_read_in inarg;
+
+        memset(&inarg, 0, sizeof(struct fuse_read_in));
+        inarg.fh = ff->fh;
+        inarg.offset = pos;
+        inarg.size = count;
+        req->in.h.opcode = FUSE_READ;
+        req->in.h.nodeid = get_node_id(inode);
+        req->inode = inode;
+        req->file = file;
+        req->in.numargs = 1;
+        req->in.args[0].size = sizeof(struct fuse_read_in);
+        req->in.args[0].value = &inarg;
+        req->out.argpages = 1;
+        req->out.argvar = 1;
+        req->out.numargs = 1;
+        req->out.args[0].size = count;
+        request_send_nonint(fc, req);
+        return req->out.args[0].size;
+}
+
+static int fuse_readpage(struct file *file, struct page *page)
+{
+        struct inode *inode = page->mapping->host;
+        struct fuse_conn *fc = get_fuse_conn(inode);
+        loff_t pos = (loff_t) page->index << PAGE_CACHE_SHIFT;
+        struct fuse_req *req = fuse_get_request_nonint(fc);
+        int err = -EINTR;
+        if (!req)
+                goto out;
+
+        req->out.page_zeroing = 1;
+        req->num_pages = 1;
+        req->pages[0] = page;
+        fuse_send_read(req, file, inode, pos, PAGE_CACHE_SIZE);
+        err = req->out.h.error;
+        fuse_put_request(fc, req);
+        if (!err)
+                SetPageUptodate(page);
+ out:
+        unlock_page(page);
+        return err;
+}
+
+static ssize_t fuse_send_write(struct fuse_req *req, struct file *file,
+                               struct inode *inode, loff_t pos, size_t count)
+{
+        struct fuse_conn *fc = get_fuse_conn(inode);
+        struct fuse_file *ff = file->private_data;
+        struct fuse_write_in inarg;
+        struct fuse_write_out outarg;
+
+        memset(&inarg, 0, sizeof(struct fuse_write_in));
+        inarg.fh = ff->fh;
+        inarg.offset = pos;
+        inarg.size = count;
+        req->in.h.opcode = FUSE_WRITE;
+        req->in.h.nodeid = get_node_id(inode);
+        req->inode = inode;
+        req->file = file;
+        req->in.argpages = 1;
+        req->in.numargs = 2;
+        req->in.args[0].size = sizeof(struct fuse_write_in);
+        req->in.args[0].value = &inarg;
+        req->in.args[1].size = count;
+        req->out.numargs = 1;
+        req->out.args[0].size = sizeof(struct fuse_write_out);
+        req->out.args[0].value = &outarg;
+        request_send_nonint(fc, req);
+        return outarg.size;
+}
+
+static int fuse_prepare_write(struct file *file, struct page *page,
+                              unsigned offset, unsigned to)
+{
+        /* No op */
+        return 0;
+}
+
+static int fuse_commit_write(struct file *file, struct page *page,
+                             unsigned offset, unsigned to)
+{
+        int err;
+        ssize_t nres;
+        unsigned count = to - offset;
+        struct inode *inode = page->mapping->host;
+        struct fuse_conn *fc = get_fuse_conn(inode);
+        loff_t pos = ((loff_t) page->index << PAGE_CACHE_SHIFT) + offset;
+        struct fuse_req *req = fuse_get_request_nonint(fc);
+        if (!req)
+                return -EINTR;
+
+        req->num_pages = 1;
+        req->pages[0] = page;
+        req->page_offset = offset;
+        nres = fuse_send_write(req, file, inode, pos, count);
+        err = req->out.h.error;
+        fuse_put_request(fc, req);
+        if (!err && nres != count)
+                err = -EIO;
+        if (!err) {
+                pos += count;
+                if (pos > i_size_read(inode))
+                        i_size_write(inode, pos);
+
+                if (offset == 0 && to == PAGE_CACHE_SIZE) {
+                        clear_page_dirty(page);
+                        SetPageUptodate(page);
+                }
+        } else if (err == -EINTR || err == -EIO)
+                fuse_invalidate_attr(inode);
+        return err;
+}
+
+static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
+{
+        if ((vma->vm_flags & VM_SHARED)) {
+                if ((vma->vm_flags & VM_WRITE))
+                        return -ENODEV;
+                else
+                        vma->vm_flags &= ~VM_MAYWRITE;
+        }
+        return generic_file_mmap(file, vma);
+}
+
+static int fuse_set_page_dirty(struct page *page)
+{
+        printk("fuse_set_page_dirty: should not happen\n");
+        dump_stack();
+        return 0;
+}
+
+static struct file_operations fuse_file_operations = {
+        .llseek         = generic_file_llseek,
+        .read           = generic_file_read,
+        .write          = generic_file_write,
+        .mmap           = fuse_file_mmap,
+        .open           = fuse_open,
+        .flush          = fuse_flush,
+        .release        = fuse_release,
+        .fsync          = fuse_fsync,
+        .sendfile       = generic_file_sendfile,
+};
+
+static struct address_space_operations fuse_file_aops  = {
+        .readpage       = fuse_readpage,
+        .prepare_write  = fuse_prepare_write,
+        .commit_write   = fuse_commit_write,
+        .set_page_dirty = fuse_set_page_dirty,
+};
+
+void fuse_init_file_inode(struct inode *inode)
+{
+        inode->i_fop = &fuse_file_operations;
+        inode->i_data.a_ops = &fuse_file_aops;
+}