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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>
This commit is contained in:
Pavel Emelyanov 2013-10-10 17:11:43 +04:00 committed by Miklos Szeredi
parent 482fce55d2
commit 6b12c1b37e
1 changed files with 73 additions and 0 deletions
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73
fs/fuse/file.c
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@ -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)