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SubjectRe: [PATCH] afs: Fix mmap
Date
I forgot to commit the patch and so lost part of it.  Full patch below.

David
---
commit 23e7d72edeeff56d7bfa47c32c9638385c90eddd
Author: David Howells <dhowells@redhat.com>
Date: Mon Dec 13 16:26:44 2021 +0000

afs: Fix mmap

Fix afs_add_open_map() to check that the vnode isn't already on the list
when it adds it. It's possible that afs_drop_open_mmap() decremented the
cb_nr_mmap counter, but hadn't yet got into the locked section to remove
it.

Also vnode->cb_mmap_link should be initialised, so fix that too.

Fixes: 6e0e99d58a65 ("afs: Fix mmap coherency vs 3rd-party changes")
Reported-by: kafs-testing+fedora34_64checkkafs-build-300@auristor.com
Suggested-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-afs@lists.infradead.org

diff --git a/fs/afs/file.c b/fs/afs/file.c
index cb6ad61eec3b..afe4b803f84b 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -514,8 +514,9 @@ static void afs_add_open_mmap(struct afs_vnode *vnode)
if (atomic_inc_return(&vnode->cb_nr_mmap) == 1) {
down_write(&vnode->volume->cell->fs_open_mmaps_lock);

- list_add_tail(&vnode->cb_mmap_link,
- &vnode->volume->cell->fs_open_mmaps);
+ if (list_empty(&vnode->cb_mmap_link))
+ list_add_tail(&vnode->cb_mmap_link,
+ &vnode->volume->cell->fs_open_mmaps);

up_write(&vnode->volume->cell->fs_open_mmaps_lock);
}
diff --git a/fs/afs/super.c b/fs/afs/super.c
index d110def8aa8e..34c68724c98b 100644
--- a/fs/afs/super.c
+++ b/fs/afs/super.c
@@ -667,6 +667,7 @@ static void afs_i_init_once(void *_vnode)
INIT_LIST_HEAD(&vnode->pending_locks);
INIT_LIST_HEAD(&vnode->granted_locks);
INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);
+ INIT_LIST_HEAD(&vnode->cb_mmap_link);
seqlock_init(&vnode->cb_lock);
}

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