From: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
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: 1cf7a1518aef ("afs: Implement shared-writeable mmap")
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
cc: linux-afs@xxxxxxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20210616154900.1958373-1-willy@xxxxxxxxxxxxx/
---
fs/afs/write.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/fs/afs/write.c b/fs/afs/write.c
index f722cb80a594..ff36800a7389 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -848,6 +848,7 @@ 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);
@@ -859,14 +860,14 @@ 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
@@ -874,7 +875,7 @@ 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));
@@ -888,8 +889,10 @@ 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;
}
/*
