Commit 9620ad86 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Linus Torvalds
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afs: Re-enable freezing once a page fault is interrupted 



If a task is killed during a page fault, it does not currently call
sb_end_pagefault(), which means that the filesystem cannot be frozen
at any time thereafter.  This may be reported by lockdep like this:

====================================
WARNING: fsstress/10757 still has locks held!
5.13.0-rc4-build4+ #91 Not tainted
------------------------------------
1 lock held by fsstress/10757:
 #0: ffff888104eac530
 (
sb_pagefaults

as filesystem freezing is modelled as a lock.

Fix this by removing all the direct returns from within the function,
and using 'ret' to indicate whether we were interrupted or successful.

Fixes: 1cf7a151 ("afs: Implement shared-writeable mmap")
Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/r/20210616154900.1958373-1-willy@infradead.org/


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b1edae0d

fs/afs/write.c

+8 −5
Original line number Diff line number Diff line
@@ -837,6 +837,7 @@ vm_fault_t afs_page_mkwrite(struct vm_fault *vmf) 
	struct inode *inode = file_inode(file);

	struct afs_vnode *vnode = AFS_FS_I(inode);

	unsigned long priv;

	vm_fault_t ret = VM_FAULT_RETRY;



	_enter("{{%llx:%llu}},{%lx}", vnode->fid.vid, vnode->fid.vnode, page->index);
@@ -848,14 +849,14 @@ vm_fault_t afs_page_mkwrite(struct vm_fault *vmf) 
#ifdef CONFIG_AFS_FSCACHE

	if (PageFsCache(page) &&

	    wait_on_page_fscache_killable(page) < 0)

		return VM_FAULT_RETRY;

		goto out;

#endif



	if (wait_on_page_writeback_killable(page))

		return VM_FAULT_RETRY;

		goto out;



	if (lock_page_killable(page) < 0)

		return VM_FAULT_RETRY;

		goto out;



	/* We mustn't change page->private until writeback is complete as that

	 * details the portion of the page we need to write back and we might
@@ -863,7 +864,7 @@ vm_fault_t afs_page_mkwrite(struct vm_fault *vmf) 
	 */

	if (wait_on_page_writeback_killable(page) < 0) {

		unlock_page(page);

		return VM_FAULT_RETRY;

		goto out;

	}



	priv = afs_page_dirty(page, 0, thp_size(page));
@@ -877,8 +878,10 @@ vm_fault_t afs_page_mkwrite(struct vm_fault *vmf) 
	}

	file_update_time(file);



	ret = VM_FAULT_LOCKED;

out:

	sb_end_pagefault(inode->i_sb);

	return VM_FAULT_LOCKED;

	return ret;

}



/*