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Commit 6fe6900e authored by Nick Piggin's avatar Nick Piggin Committed by Linus Torvalds
Browse files

mm: make read_cache_page synchronous 



Ensure pages are uptodate after returning from read_cache_page, which allows
us to cut out most of the filesystem-internal PageUptodate calls.

I didn't have a great look down the call chains, but this appears to fixes 7
possible use-before uptodate in hfs, 2 in hfsplus, 1 in jfs, a few in
ecryptfs, 1 in jffs2, and a possible cleared data overwritten with readpage in
block2mtd.  All depending on whether the filler is async and/or can return
with a !uptodate page.

Signed-off-by: default avatarNick Piggin <npiggin@suse.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 714b8171

drivers/mtd/devices/block2mtd.c

+2 −4
Original line number Diff line number Diff line
@@ -42,11 +42,9 @@ static LIST_HEAD(blkmtd_device_list); 


static struct page *page_read(struct address_space *mapping, int index)

{

	filler_t *filler = (filler_t*)mapping->a_ops->readpage;

	return read_cache_page(mapping, index, filler, NULL);

	return read_mapping_page(mapping, index, NULL);

}





/* erase a specified part of the device */

static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len)

{

fs/afs/dir.c

+0 −3
Original line number Diff line number Diff line
@@ -194,10 +194,7 @@ static struct page *afs_dir_get_page(struct inode *dir, unsigned long index, 


	page = read_mapping_page(dir->i_mapping, index, &file);

	if (!IS_ERR(page)) {

		wait_on_page_locked(page);

		kmap(page);

		if (!PageUptodate(page))

			goto fail;

		if (!PageChecked(page))

			afs_dir_check_page(dir, page);

		if (PageError(page))

fs/afs/mntpt.c

+4 −7
Original line number Diff line number Diff line
@@ -68,13 +68,11 @@ int afs_mntpt_check_symlink(struct afs_vnode *vnode, struct key *key) 
	}



	ret = -EIO;

	wait_on_page_locked(page);

	buf = kmap(page);

	if (!PageUptodate(page))

		goto out_free;

	if (PageError(page))

		goto out_free;



	buf = kmap(page);



	/* examine the symlink's contents */

	size = vnode->status.size;

	_debug("symlink to %*.*s", (int) size, (int) size, buf);
@@ -91,8 +89,8 @@ int afs_mntpt_check_symlink(struct afs_vnode *vnode, struct key *key) 


	ret = 0;



out_free:

	kunmap(page);

out_free:

	page_cache_release(page);

out:

	_leave(" = %d", ret);
@@ -171,8 +169,7 @@ static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt) 
	}



	ret = -EIO;

	wait_on_page_locked(page);

	if (!PageUptodate(page) || PageError(page))

	if (PageError(page))

		goto error;



	buf = kmap(page);

fs/cramfs/inode.c

+2 −1
Original line number Diff line number Diff line
@@ -180,7 +180,8 @@ static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned i 
		struct page *page = NULL;



		if (blocknr + i < devsize) {

			page = read_mapping_page(mapping, blocknr + i, NULL);

			page = read_mapping_page_async(mapping, blocknr + i,

									NULL);

			/* synchronous error? */

			if (IS_ERR(page))

				page = NULL;

fs/ecryptfs/mmap.c

+1 −10
Original line number Diff line number Diff line
@@ -46,7 +46,6 @@ struct kmem_cache *ecryptfs_lower_page_cache; 
 */

static struct page *ecryptfs_get1page(struct file *file, int index)

{

	struct page *page;

	struct dentry *dentry;

	struct inode *inode;

	struct address_space *mapping;
@@ -54,14 +53,7 @@ static struct page *ecryptfs_get1page(struct file *file, int index) 
	dentry = file->f_path.dentry;

	inode = dentry->d_inode;

	mapping = inode->i_mapping;

	page = read_cache_page(mapping, index,

			       (filler_t *)mapping->a_ops->readpage,

			       (void *)file);

	if (IS_ERR(page))

		goto out;

	wait_on_page_locked(page);

out:

	return page;

	return read_mapping_page(mapping, index, (void *)file);

}



static
@@ -233,7 +225,6 @@ int ecryptfs_do_readpage(struct file *file, struct page *page, 
		ecryptfs_printk(KERN_ERR, "Error reading from page cache\n");

		goto out;

	}

	wait_on_page_locked(lower_page);

	page_data = kmap_atomic(page, KM_USER0);

	lower_page_data = kmap_atomic(lower_page, KM_USER1);

	memcpy(page_data, lower_page_data, PAGE_CACHE_SIZE);