[PATCH 13/14] ceph: Fix race between hole punch and page fault
From: Jan Kara <jack@suse.cz>
Date: 2021-07-12 16:58:04
Also in:
ceph-devel, linux-cifs, linux-ext4, linux-f2fs-devel, linux-fsdevel, linux-xfs
Subsystem:
ceph distributed file system client (ceph), filesystems (vfs and infrastructure), the rest · Maintainers:
Ilya Dryomov, Alex Markuze, Viacheslav Dubeyko, Alexander Viro, Christian Brauner, Linus Torvalds
Ceph has a following race between hole punching and page fault:
CPU1 CPU2
ceph_fallocate()
...
ceph_zero_pagecache_range()
ceph_filemap_fault()
faults in page in the range being
punched
ceph_zero_objects()
And now we have a page in punched range with invalid data. Fix the
problem by using mapping->invalidate_lock similarly to other
filesystems. Note that using invalidate_lock also fixes a similar race
wrt ->readpage().
CC: Jeff Layton <jlayton@kernel.org>
CC: ceph-devel@vger.kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
---
fs/ceph/addr.c | 9 ++++++---
fs/ceph/file.c | 2 ++
2 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index a1e2813731d1..7e7a897ae0d3 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c@@ -1395,9 +1395,11 @@ static vm_fault_t ceph_filemap_fault(struct vm_fault *vmf) ret = VM_FAULT_SIGBUS; } else { struct address_space *mapping = inode->i_mapping; - struct page *page = find_or_create_page(mapping, 0, - mapping_gfp_constraint(mapping, - ~__GFP_FS)); + struct page *page; + + filemap_invalidate_lock_shared(mapping); + page = find_or_create_page(mapping, 0, + mapping_gfp_constraint(mapping, ~__GFP_FS)); if (!page) { ret = VM_FAULT_OOM; goto out_inline;
@@ -1418,6 +1420,7 @@ static vm_fault_t ceph_filemap_fault(struct vm_fault *vmf) vmf->page = page; ret = VM_FAULT_MAJOR | VM_FAULT_LOCKED; out_inline: + filemap_invalidate_unlock_shared(mapping); dout("filemap_fault %p %llu read inline data ret %x\n", inode, off, ret); }
diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index d1755ac1d964..e1d605a02d4a 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c@@ -2088,6 +2088,7 @@ static long ceph_fallocate(struct file *file, int mode, if (ret < 0) goto unlock; + filemap_invalidate_lock(inode->i_mapping); ceph_zero_pagecache_range(inode, offset, length); ret = ceph_zero_objects(inode, offset, length);
@@ -2100,6 +2101,7 @@ static long ceph_fallocate(struct file *file, int mode, if (dirty) __mark_inode_dirty(inode, dirty); } + filemap_invalidate_unlock(inode->i_mapping); ceph_put_cap_refs(ci, got); unlock:
--
2.26.2