fuse: Implement write_begin/write_end callbacks
The .write_begin and .write_end are requiered to use generic routines (generic_file_aio_write --> ... --> generic_perform_write) for buffered writes. Signed-off-by: Maxim Patlasov <MPatlasov@parallels.com> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
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@ -1952,6 +1952,77 @@ out:
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return err;
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}
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/*
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* It's worthy to make sure that space is reserved on disk for the write,
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* but how to implement it without killing performance need more thinking.
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*/
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static int fuse_write_begin(struct file *file, struct address_space *mapping,
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loff_t pos, unsigned len, unsigned flags,
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struct page **pagep, void **fsdata)
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{
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pgoff_t index = pos >> PAGE_CACHE_SHIFT;
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struct fuse_conn *fc = get_fuse_conn(file->f_dentry->d_inode);
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struct page *page;
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loff_t fsize;
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int err = -ENOMEM;
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WARN_ON(!fc->writeback_cache);
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page = grab_cache_page_write_begin(mapping, index, flags);
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if (!page)
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goto error;
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fuse_wait_on_page_writeback(mapping->host, page->index);
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if (PageUptodate(page) || len == PAGE_CACHE_SIZE)
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goto success;
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/*
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* Check if the start this page comes after the end of file, in which
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* case the readpage can be optimized away.
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*/
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fsize = i_size_read(mapping->host);
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if (fsize <= (pos & PAGE_CACHE_MASK)) {
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size_t off = pos & ~PAGE_CACHE_MASK;
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if (off)
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zero_user_segment(page, 0, off);
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goto success;
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}
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err = fuse_do_readpage(file, page);
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if (err)
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goto cleanup;
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success:
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*pagep = page;
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return 0;
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cleanup:
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unlock_page(page);
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page_cache_release(page);
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error:
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return err;
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}
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static int fuse_write_end(struct file *file, struct address_space *mapping,
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loff_t pos, unsigned len, unsigned copied,
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struct page *page, void *fsdata)
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{
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struct inode *inode = page->mapping->host;
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if (!PageUptodate(page)) {
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/* Zero any unwritten bytes at the end of the page */
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size_t endoff = (pos + copied) & ~PAGE_CACHE_MASK;
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if (endoff)
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zero_user_segment(page, endoff, PAGE_CACHE_SIZE);
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SetPageUptodate(page);
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}
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fuse_write_update_size(inode, pos + copied);
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set_page_dirty(page);
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unlock_page(page);
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page_cache_release(page);
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return copied;
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}
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static int fuse_launder_page(struct page *page)
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{
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int err = 0;
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@ -2979,6 +3050,8 @@ static const struct address_space_operations fuse_file_aops = {
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.set_page_dirty = __set_page_dirty_nobuffers,
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.bmap = fuse_bmap,
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.direct_IO = fuse_direct_IO,
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.write_begin = fuse_write_begin,
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.write_end = fuse_write_end,
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};
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void fuse_init_file_inode(struct inode *inode)
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