> On 12 Sep 2017, at 21:21, Jeff Layton <jlayton@xxxxxxxxxx> wrote:
>
> On Tue, 2017-09-12 at 10:53 +0800, Yan, Zheng wrote:
>> file locks are tracked by inode's auth mds. releasing auth caps
>> is equivalent to releasing all file locks.
>>
>> Signed-off-by: "Yan, Zheng" <zyan@xxxxxxxxxx>
>> ---
>> fs/ceph/inode.c | 1 +
>> fs/ceph/locks.c | 62 ++++++++++++++++++++++++++++++++++++++++++++--------
>> fs/ceph/mds_client.c | 2 ++
>> fs/ceph/super.h | 1 +
>> 4 files changed, 57 insertions(+), 9 deletions(-)
>>
>> diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
>> index 373dab5173ca..c70b26d2bf8a 100644
>> --- a/fs/ceph/inode.c
>> +++ b/fs/ceph/inode.c
>> @@ -492,6 +492,7 @@ struct inode *ceph_alloc_inode(struct super_block *sb)
>> ci->i_wb_ref = 0;
>> ci->i_wrbuffer_ref = 0;
>> ci->i_wrbuffer_ref_head = 0;
>> + atomic_set(&ci->i_filelock_ref, 0);
>> ci->i_shared_gen = 0;
>> ci->i_rdcache_gen = 0;
>> ci->i_rdcache_revoking = 0;
>> diff --git a/fs/ceph/locks.c b/fs/ceph/locks.c
>> index 64ae74472046..69f731e75302 100644
>> --- a/fs/ceph/locks.c
>> +++ b/fs/ceph/locks.c
>> @@ -29,19 +29,46 @@ void __init ceph_flock_init(void)
>> get_random_bytes(&lock_secret, sizeof(lock_secret));
>> }
>>
>> +static void ceph_fl_copy_lock(struct file_lock *dst, struct file_lock *src)
>> +{
>> + struct inode *inode = file_inode(src->fl_file);
>> + atomic_inc(&ceph_inode(inode)->i_filelock_ref);
>> +}
>> +
>> +static void ceph_fl_release_lock(struct file_lock *fl)
>> +{
>> + struct inode *inode = file_inode(fl->fl_file);
>> + atomic_dec(&ceph_inode(inode)->i_filelock_ref);
>> +}
>> +
>> +static const struct file_lock_operations ceph_fl_lock_ops = {
>> + .fl_copy_lock = ceph_fl_copy_lock,
>> + .fl_release_private = ceph_fl_release_lock,
>> +};
>> +
>> /**
>> * Implement fcntl and flock locking functions.
>> */
>> -static int ceph_lock_message(u8 lock_type, u16 operation, struct file *file,
>> +static int ceph_lock_message(u8 lock_type, u16 operation, struct inode *inode,
>> int cmd, u8 wait, struct file_lock *fl)
>> {
>> - struct inode *inode = file_inode(file);
>> struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc;
>> struct ceph_mds_request *req;
>> int err;
>> u64 length = 0;
>> u64 owner;
>>
>> + if (operation == CEPH_MDS_OP_SETFILELOCK) {
>> + /*
>> + * increasing i_filelock_ref closes race window between
>> + * handling request reply and adding file_lock struct to
>> + * inode. Otherwise, i_auth_cap may get trimmed in the
>> + * window. Caller function will decrease the counter.
>> + */
>> + fl->fl_ops = &ceph_fl_lock_ops;
>> + atomic_inc(&ceph_inode(inode)->i_filelock_ref);
>> + }
>> +
>> if (operation != CEPH_MDS_OP_SETFILELOCK || cmd == CEPH_LOCK_UNLOCK)
>> wait = 0;
>>
>> @@ -179,10 +206,11 @@ static int ceph_lock_wait_for_completion(struct ceph_mds_client *mdsc,
>> */
>> int ceph_lock(struct file *file, int cmd, struct file_lock *fl)
>> {
>> - u8 lock_cmd;
>> + struct inode *inode = file_inode(file);
>> int err;
>> - u8 wait = 0;
>> u16 op = CEPH_MDS_OP_SETFILELOCK;
>> + u8 lock_cmd;
>> + u8 wait = 0;
>>
>> if (!(fl->fl_flags & FL_POSIX))
>> return -ENOLCK;
>> @@ -198,6 +226,17 @@ int ceph_lock(struct file *file, int cmd, struct file_lock *fl)
>> else if (IS_SETLKW(cmd))
>> wait = 1;
>>
>> + if (op == CEPH_MDS_OP_SETFILELOCK) {
>> + /*
>> + * increasing i_filelock_ref closes race window between
>> + * handling request reply and adding file_lock struct to
>> + * inode. Otherwise, i_auth_cap may get trimmed in the
>> + * window. Caller function will decrease the counter.
>> + */
>> + fl->fl_ops = &ceph_fl_lock_ops;
>> + atomic_inc(&ceph_inode(inode)->i_filelock_ref);
>> + }
>> +
>> if (F_RDLCK == fl->fl_type)
>> lock_cmd = CEPH_LOCK_SHARED;
>> else if (F_WRLCK == fl->fl_type)
>> @@ -205,7 +244,7 @@ int ceph_lock(struct file *file, int cmd, struct file_lock *fl)
>> else
>> lock_cmd = CEPH_LOCK_UNLOCK;
>>
>> - err = ceph_lock_message(CEPH_LOCK_FCNTL, op, file, lock_cmd, wait, fl);
>> + err = ceph_lock_message(CEPH_LOCK_FCNTL, op, inode, lock_cmd, wait, fl);
>> if (!err) {
>> if (op != CEPH_MDS_OP_GETFILELOCK) {
>> dout("mds locked, locking locally");
>> @@ -214,7 +253,7 @@ int ceph_lock(struct file *file, int cmd, struct file_lock *fl)
>> /* undo! This should only happen if
>> * the kernel detects local
>> * deadlock. */
>> - ceph_lock_message(CEPH_LOCK_FCNTL, op, file,
>> + ceph_lock_message(CEPH_LOCK_FCNTL, op, inode,
>> CEPH_LOCK_UNLOCK, 0, fl);
>> dout("got %d on posix_lock_file, undid lock",
>> err);
>> @@ -226,8 +265,9 @@ int ceph_lock(struct file *file, int cmd, struct file_lock *fl)
>>
>> int ceph_flock(struct file *file, int cmd, struct file_lock *fl)
>> {
>> - u8 lock_cmd;
>> + struct inode *inode = file_inode(file);
>> int err;
>> + u8 lock_cmd;
>> u8 wait = 0;
>>
>> if (!(fl->fl_flags & FL_FLOCK))
>> @@ -238,6 +278,10 @@ int ceph_flock(struct file *file, int cmd, struct file_lock *fl)
>>
>> dout("ceph_flock, fl_file: %p", fl->fl_file);
>>
>> + /* see comment in ceph_lock */
>> + fl->fl_ops = &ceph_fl_lock_ops;
>> + atomic_inc(&ceph_inode(inode)->i_filelock_ref);
>> +
>> if (IS_SETLKW(cmd))
>> wait = 1;
>>
>> @@ -249,13 +293,13 @@ int ceph_flock(struct file *file, int cmd, struct file_lock *fl)
>> lock_cmd = CEPH_LOCK_UNLOCK;
>>
>> err = ceph_lock_message(CEPH_LOCK_FLOCK, CEPH_MDS_OP_SETFILELOCK,
>> - file, lock_cmd, wait, fl);
>> + inode, lock_cmd, wait, fl);
>> if (!err) {
>> err = locks_lock_file_wait(file, fl);
>> if (err) {
>> ceph_lock_message(CEPH_LOCK_FLOCK,
>> CEPH_MDS_OP_SETFILELOCK,
>> - file, CEPH_LOCK_UNLOCK, 0, fl);
>> + inode, CEPH_LOCK_UNLOCK, 0, fl);
>> dout("got %d on locks_lock_file_wait, undid lock", err);
>> }
>> }
>> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
>> index 9dd6b836ac9e..6146af4ed03c 100644
>> --- a/fs/ceph/mds_client.c
>> +++ b/fs/ceph/mds_client.c
>> @@ -1461,6 +1461,8 @@ static int trim_caps_cb(struct inode *inode, struct ceph_cap *cap, void *arg)
>> goto out;
>> if ((used | wanted) & CEPH_CAP_ANY_WR)
>> goto out;
>> + if (atomic_read(&ci->i_filelock_ref) > 0)
>> + goto out;
>
> Is there a potential race here? Could i_filelock_ref do a 0->1
> transition just after you check it?
It’s possible, but it does not hurt. Because i_filelock_ref gets increased before sending mds request.
The extra reference gets dropped after setup the kernel file_lock data structure. The reply of mds
request re-add auth cap if auth caps was dropped.
Regards
Yan, Zheng
>
>> }
>> /* The inode has cached pages, but it's no longer used.
>> * we can safely drop it */
>> diff --git a/fs/ceph/super.h b/fs/ceph/super.h
>> index 279a2f401cf5..9e0de8264257 100644
>> --- a/fs/ceph/super.h
>> +++ b/fs/ceph/super.h
>> @@ -351,6 +351,7 @@ struct ceph_inode_info {
>> int i_pin_ref;
>> int i_rd_ref, i_rdcache_ref, i_wr_ref, i_wb_ref;
>> int i_wrbuffer_ref, i_wrbuffer_ref_head;
>> + atomic_t i_filelock_ref;
>> u32 i_shared_gen; /* increment each time we get FILE_SHARED */
>> u32 i_rdcache_gen; /* incremented each time we get FILE_CACHE. */
>> u32 i_rdcache_revoking; /* RDCACHE gen to async invalidate, if any */
>
> --
> Jeff Layton <jlayton@xxxxxxxxxx>
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