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Subject[PATCH 2/2 v2] ceph: use a xarray to record all the opened files for each inode
Date
From: Xiubo Li <xiubli@redhat.com>

When releasing the file locks the fl->fl_file memory could be
already released by another thread in filp_close(), so we couldn't
depend on fl->fl_file to get the inode. Just use a xarray to record
the opened files for each inode.

Cc: stable@vger.kernel.org
URL: https://tracker.ceph.com/issues/57986
Signed-off-by: Xiubo Li <xiubli@redhat.com>
---
fs/ceph/file.c | 9 +++++++++
fs/ceph/inode.c | 4 ++++
fs/ceph/locks.c | 17 ++++++++++++++++-
fs/ceph/super.h | 4 ++++
4 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index 85afcbbb5648..cb4a9c52df27 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -231,6 +231,13 @@ static int ceph_init_file_info(struct inode *inode, struct file *file,
fi->flags |= CEPH_F_SYNC;

file->private_data = fi;
+
+ ret = xa_insert(&ci->i_opened_files, (unsigned long)file,
+ CEPH_FILP_AVAILABLE, GFP_KERNEL);
+ if (ret) {
+ kmem_cache_free(ceph_file_cachep, fi);
+ return ret;
+ }
}

ceph_get_fmode(ci, fmode, 1);
@@ -932,6 +939,8 @@ int ceph_release(struct inode *inode, struct file *file)
dout("release inode %p regular file %p\n", inode, file);
WARN_ON(!list_empty(&fi->rw_contexts));

+ xa_erase(&ci->i_opened_files, (unsigned long)file);
+
ceph_fscache_unuse_cookie(inode, file->f_mode & FMODE_WRITE);
ceph_put_fmode(ci, fi->fmode, 1);

diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 77b0cd9af370..554450838e44 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -619,6 +619,8 @@ struct inode *ceph_alloc_inode(struct super_block *sb)
INIT_LIST_HEAD(&ci->i_unsafe_iops);
spin_lock_init(&ci->i_unsafe_lock);

+ xa_init(&ci->i_opened_files);
+
ci->i_snap_realm = NULL;
INIT_LIST_HEAD(&ci->i_snap_realm_item);
INIT_LIST_HEAD(&ci->i_snap_flush_item);
@@ -637,6 +639,8 @@ void ceph_free_inode(struct inode *inode)
{
struct ceph_inode_info *ci = ceph_inode(inode);

+ xa_destroy(&ci->i_opened_files);
+
kfree(ci->i_symlink);
#ifdef CONFIG_FS_ENCRYPTION
kfree(ci->fscrypt_auth);
diff --git a/fs/ceph/locks.c b/fs/ceph/locks.c
index d8385dd0076e..a176a30badd0 100644
--- a/fs/ceph/locks.c
+++ b/fs/ceph/locks.c
@@ -42,9 +42,10 @@ static void ceph_fl_copy_lock(struct file_lock *dst, struct file_lock *src)

static void ceph_fl_release_lock(struct file_lock *fl)
{
- struct ceph_file_info *fi = fl->fl_file->private_data;
struct inode *inode = fl->fl_u.ceph_fl.fl_inode;
struct ceph_inode_info *ci;
+ struct ceph_file_info *fi;
+ void *val;

/*
* If inode is NULL it should be a request file_lock,
@@ -54,6 +55,20 @@ static void ceph_fl_release_lock(struct file_lock *fl)
return;

ci = ceph_inode(inode);
+
+ /*
+ * For Posix-style locks, it may race between filp_close()s,
+ * and it's possible that the 'file' memory pointed by
+ * 'fl->fl_file' has been released. If so just skip it.
+ */
+ rcu_read_lock();
+ val = xa_load(&ci->i_opened_files, (unsigned long)fl->fl_file);
+ if (val == CEPH_FILP_AVAILABLE) {
+ fi = fl->fl_file->private_data;
+ atomic_dec(&fi->num_locks);
+ }
+ rcu_read_unlock();
+
if (atomic_dec_and_test(&ci->i_filelock_ref)) {
/* clear error when all locks are released */
spin_lock(&ci->i_ceph_lock);
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index 7b75a84ba48d..b3e89192cbec 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -329,6 +329,8 @@ struct ceph_inode_xattrs_info {
u64 version, index_version;
};

+#define CEPH_FILP_AVAILABLE xa_mk_value(1)
+
/*
* Ceph inode.
*/
@@ -434,6 +436,8 @@ struct ceph_inode_info {
struct list_head i_unsafe_iops; /* uncommitted mds inode ops */
spinlock_t i_unsafe_lock;

+ struct xarray i_opened_files;
+
union {
struct ceph_snap_realm *i_snap_realm; /* snap realm (if caps) */
struct ceph_snapid_map *i_snapid_map; /* snapid -> dev_t */
--
2.31.1
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