From 6b12c1b37e5556af073c1ebfa04c1f9df3a2beaf Mon Sep 17 00:00:00 2001 From: Pavel Emelyanov Date: Thu, 10 Oct 2013 17:11:43 +0400 Subject: 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 Signed-off-by: Miklos Szeredi --- fs/fuse/file.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 73 insertions(+) (limited to 'fs/fuse') diff --git a/fs/fuse/file.c b/fs/fuse/file.c index b1873b5..d857530 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -1952,6 +1952,77 @@ out: return err; } +/* + * It's worthy to make sure that space is reserved on disk for the write, + * but how to implement it without killing performance need more thinking. + */ +static int fuse_write_begin(struct file *file, struct address_space *mapping, + loff_t pos, unsigned len, unsigned flags, + struct page **pagep, void **fsdata) +{ + pgoff_t index = pos >> PAGE_CACHE_SHIFT; + struct fuse_conn *fc = get_fuse_conn(file->f_dentry->d_inode); + struct page *page; + loff_t fsize; + int err = -ENOMEM; + + WARN_ON(!fc->writeback_cache); + + page = grab_cache_page_write_begin(mapping, index, flags); + if (!page) + goto error; + + fuse_wait_on_page_writeback(mapping->host, page->index); + + if (PageUptodate(page) || len == PAGE_CACHE_SIZE) + goto success; + /* + * Check if the start this page comes after the end of file, in which + * case the readpage can be optimized away. + */ + fsize = i_size_read(mapping->host); + if (fsize <= (pos & PAGE_CACHE_MASK)) { + size_t off = pos & ~PAGE_CACHE_MASK; + if (off) + zero_user_segment(page, 0, off); + goto success; + } + err = fuse_do_readpage(file, page); + if (err) + goto cleanup; +success: + *pagep = page; + return 0; + +cleanup: + unlock_page(page); + page_cache_release(page); +error: + return err; +} + +static int fuse_write_end(struct file *file, struct address_space *mapping, + loff_t pos, unsigned len, unsigned copied, + struct page *page, void *fsdata) +{ + struct inode *inode = page->mapping->host; + + if (!PageUptodate(page)) { + /* Zero any unwritten bytes at the end of the page */ + size_t endoff = (pos + copied) & ~PAGE_CACHE_MASK; + if (endoff) + zero_user_segment(page, endoff, PAGE_CACHE_SIZE); + SetPageUptodate(page); + } + + fuse_write_update_size(inode, pos + copied); + set_page_dirty(page); + unlock_page(page); + page_cache_release(page); + + return copied; +} + static int fuse_launder_page(struct page *page) { int err = 0; @@ -2979,6 +3050,8 @@ static const struct address_space_operations fuse_file_aops = { .set_page_dirty = __set_page_dirty_nobuffers, .bmap = fuse_bmap, .direct_IO = fuse_direct_IO, + .write_begin = fuse_write_begin, + .write_end = fuse_write_end, }; void fuse_init_file_inode(struct inode *inode) -- cgit v1.1