Commit e8e581a8 authored by David Howells's avatar David Howells
Browse files

afs: Handle a short write to an AFS page 



Handle the situation where afs_write_begin() is told to expect that a
full-page write will be made, but this doesn't happen (EFAULT, CTRL-C,
etc.), and so afs_write_end() sees a partial write took place.  Currently,
no attempt is to deal with the discrepency.

Fix this by loading the gap from the server.

Reported-by: default avatarAl Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
parent 3448e652

fs/afs/fsclient.c

+3 −1
Original line number Diff line number Diff line
@@ -393,8 +393,10 @@ static int afs_deliver_fs_fetch_data(struct afs_call *call) 
			if (req->remain > 0) {

				call->offset = 0;

				req->index++;

				if (req->index >= req->nr_pages)

				if (req->index >= req->nr_pages) {

					call->unmarshall = 4;

					goto begin_discard;

				}

				goto begin_page;

			}

		}

fs/afs/internal.h

+1 −1
Original line number Diff line number Diff line
@@ -130,7 +130,7 @@ struct afs_call_type { 
 */

struct afs_read {

	loff_t			pos;		/* Where to start reading */

	loff_t			len;		/* How much to read */

	loff_t			len;		/* How much we're asking for */

	loff_t			actual_len;	/* How much we're actually getting */

	atomic_t		usage;

	unsigned int		remain;		/* Amount remaining */

fs/afs/write.c

+19 −9
Original line number Diff line number Diff line
@@ -84,10 +84,9 @@ void afs_put_writeback(struct afs_writeback *wb) 
 * partly or wholly fill a page that's under preparation for writing

 */

static int afs_fill_page(struct afs_vnode *vnode, struct key *key,

			 loff_t pos, struct page *page)

			 loff_t pos, unsigned int len, struct page *page)

{

	struct afs_read *req;

	loff_t i_size;

	int ret;



	_enter(",,%llu", (unsigned long long)pos);
@@ -99,16 +98,11 @@ static int afs_fill_page(struct afs_vnode *vnode, struct key *key, 


	atomic_set(&req->usage, 1);

	req->pos = pos;

	req->len = len;

	req->nr_pages = 1;

	req->pages[0] = page;

	get_page(page);



	i_size = i_size_read(&vnode->vfs_inode);

	if (pos + PAGE_SIZE > i_size)

		req->len = i_size - pos;

	else

		req->len = PAGE_SIZE;



	ret = afs_vnode_fetch_data(vnode, key, req);

	afs_put_read(req);

	if (ret < 0) {
@@ -164,7 +158,7 @@ int afs_write_begin(struct file *file, struct address_space *mapping, 
	/* page won't leak in error case: it eventually gets cleaned off LRU */



	if (!PageUptodate(page) && len != PAGE_SIZE) {

		ret = afs_fill_page(vnode, key, index << PAGE_SHIFT, page);

		ret = afs_fill_page(vnode, key, pos & PAGE_MASK, PAGE_SIZE, page);

		if (ret < 0) {

			kfree(candidate);

			_leave(" = %d [prep]", ret);
@@ -258,7 +252,9 @@ int afs_write_end(struct file *file, struct address_space *mapping, 
		  struct page *page, void *fsdata)

{

	struct afs_vnode *vnode = AFS_FS_I(file_inode(file));

	struct key *key = file->private_data;

	loff_t i_size, maybe_i_size;

	int ret;



	_enter("{%x:%u},{%lx}",

	       vnode->fid.vid, vnode->fid.vnode, page->index);
@@ -274,6 +270,20 @@ int afs_write_end(struct file *file, struct address_space *mapping, 
		spin_unlock(&vnode->writeback_lock);

	}



	if (!PageUptodate(page)) {

		if (copied < len) {

			/* Try and load any missing data from the server.  The

			 * unmarshalling routine will take care of clearing any

			 * bits that are beyond the EOF.

			 */

			ret = afs_fill_page(vnode, key, pos + copied,

					    len - copied, page);

			if (ret < 0)

				return ret;

		}

		SetPageUptodate(page);

	}



	set_page_dirty(page);

	if (PageDirty(page))

		_debug("dirtied");

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