fuse: implement perform_write
Introduce fuse_perform_write. With fusexmp (a passthrough filesystem), large
(1MB) writes into a backing tmpfs filesystem are sped up by almost 4 times
(256MB/s vs 71MB/s).
[mszeredi@suse.cz]:
- split into smaller functions
- testing
- duplicate generic_file_aio_write(), so that there's no need to add a
new ->perform_write() a_op. Comment from hch.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index f0f0f27..c5b5982 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -677,6 +677,198 @@
return res;
}
+static size_t fuse_send_write_pages(struct fuse_req *req, struct file *file,
+ struct inode *inode, loff_t pos,
+ size_t count)
+{
+ size_t res;
+ unsigned offset;
+ unsigned i;
+
+ for (i = 0; i < req->num_pages; i++)
+ fuse_wait_on_page_writeback(inode, req->pages[i]->index);
+
+ res = fuse_send_write(req, file, inode, pos, count, NULL);
+
+ offset = req->page_offset;
+ count = res;
+ for (i = 0; i < req->num_pages; i++) {
+ struct page *page = req->pages[i];
+
+ if (!req->out.h.error && !offset && count >= PAGE_CACHE_SIZE)
+ SetPageUptodate(page);
+
+ if (count > PAGE_CACHE_SIZE - offset)
+ count -= PAGE_CACHE_SIZE - offset;
+ else
+ count = 0;
+ offset = 0;
+
+ unlock_page(page);
+ page_cache_release(page);
+ }
+
+ return res;
+}
+
+static ssize_t fuse_fill_write_pages(struct fuse_req *req,
+ struct address_space *mapping,
+ struct iov_iter *ii, loff_t pos)
+{
+ struct fuse_conn *fc = get_fuse_conn(mapping->host);
+ unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
+ size_t count = 0;
+ int err;
+
+ req->page_offset = offset;
+
+ do {
+ size_t tmp;
+ struct page *page;
+ pgoff_t index = pos >> PAGE_CACHE_SHIFT;
+ size_t bytes = min_t(size_t, PAGE_CACHE_SIZE - offset,
+ iov_iter_count(ii));
+
+ bytes = min_t(size_t, bytes, fc->max_write - count);
+
+ again:
+ err = -EFAULT;
+ if (iov_iter_fault_in_readable(ii, bytes))
+ break;
+
+ err = -ENOMEM;
+ page = __grab_cache_page(mapping, index);
+ if (!page)
+ break;
+
+ pagefault_disable();
+ tmp = iov_iter_copy_from_user_atomic(page, ii, offset, bytes);
+ pagefault_enable();
+ flush_dcache_page(page);
+
+ if (!tmp) {
+ unlock_page(page);
+ page_cache_release(page);
+ bytes = min(bytes, iov_iter_single_seg_count(ii));
+ goto again;
+ }
+
+ err = 0;
+ req->pages[req->num_pages] = page;
+ req->num_pages++;
+
+ iov_iter_advance(ii, tmp);
+ count += tmp;
+ pos += tmp;
+ offset += tmp;
+ if (offset == PAGE_CACHE_SIZE)
+ offset = 0;
+
+ } while (iov_iter_count(ii) && count < fc->max_write &&
+ req->num_pages < FUSE_MAX_PAGES_PER_REQ && offset == 0);
+
+ return count > 0 ? count : err;
+}
+
+static ssize_t fuse_perform_write(struct file *file,
+ struct address_space *mapping,
+ struct iov_iter *ii, loff_t pos)
+{
+ struct inode *inode = mapping->host;
+ struct fuse_conn *fc = get_fuse_conn(inode);
+ int err = 0;
+ ssize_t res = 0;
+
+ if (is_bad_inode(inode))
+ return -EIO;
+
+ do {
+ struct fuse_req *req;
+ ssize_t count;
+
+ req = fuse_get_req(fc);
+ if (IS_ERR(req)) {
+ err = PTR_ERR(req);
+ break;
+ }
+
+ count = fuse_fill_write_pages(req, mapping, ii, pos);
+ if (count <= 0) {
+ err = count;
+ } else {
+ size_t num_written;
+
+ num_written = fuse_send_write_pages(req, file, inode,
+ pos, count);
+ err = req->out.h.error;
+ if (!err) {
+ res += num_written;
+ pos += num_written;
+
+ /* break out of the loop on short write */
+ if (num_written != count)
+ err = -EIO;
+ }
+ }
+ fuse_put_request(fc, req);
+ } while (!err && iov_iter_count(ii));
+
+ if (res > 0)
+ fuse_write_update_size(inode, pos);
+
+ fuse_invalidate_attr(inode);
+
+ return res > 0 ? res : err;
+}
+
+static ssize_t fuse_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
+ unsigned long nr_segs, loff_t pos)
+{
+ struct file *file = iocb->ki_filp;
+ struct address_space *mapping = file->f_mapping;
+ size_t count = 0;
+ ssize_t written = 0;
+ struct inode *inode = mapping->host;
+ ssize_t err;
+ struct iov_iter i;
+
+ WARN_ON(iocb->ki_pos != pos);
+
+ err = generic_segment_checks(iov, &nr_segs, &count, VERIFY_READ);
+ if (err)
+ return err;
+
+ mutex_lock(&inode->i_mutex);
+ vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
+
+ /* We can write back this queue in page reclaim */
+ current->backing_dev_info = mapping->backing_dev_info;
+
+ err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
+ if (err)
+ goto out;
+
+ if (count == 0)
+ goto out;
+
+ err = remove_suid(file->f_path.dentry);
+ if (err)
+ goto out;
+
+ file_update_time(file);
+
+ iov_iter_init(&i, iov, nr_segs, count, 0);
+ written = fuse_perform_write(file, mapping, &i, pos);
+ if (written >= 0)
+ iocb->ki_pos = pos + written;
+
+out:
+ current->backing_dev_info = NULL;
+ mutex_unlock(&inode->i_mutex);
+
+ return written ? written : err;
+}
+
static void fuse_release_user_pages(struct fuse_req *req, int write)
{
unsigned i;
@@ -1203,7 +1395,7 @@
.read = do_sync_read,
.aio_read = fuse_file_aio_read,
.write = do_sync_write,
- .aio_write = generic_file_aio_write,
+ .aio_write = fuse_file_aio_write,
.mmap = fuse_file_mmap,
.open = fuse_open,
.flush = fuse_flush,