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ceph: fix possible deadlock when holding Fwb to get inline_data

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1, mount with wsync.
2, create a file with O_RDWR, and the request was sent to mds.0:

   ceph_atomic_open()-->
     ceph_mdsc_do_request(openc)
     finish_open(file, dentry, ceph_open)-->
       ceph_open()-->
         ceph_init_file()-->
           ceph_init_file_info()-->
             ceph_uninline_data()-->
             {
               ...
               if (inline_version == 1 || /* initial version, no data */
                   inline_version == CEPH_INLINE_NONE)
                     goto out_unlock;
               ...
             }

The inline_version will be 1, which is the initial version for the
new create file. And here the ci->i_inline_version will keep with 1,
it's buggy.

3, buffer write to the file immediately:

   ceph_write_iter()-->
     ceph_get_caps(file, need=Fw, want=Fb, ...);
     generic_perform_write()-->
       a_ops->write_begin()-->
         ceph_write_begin()-->
           netfs_write_begin()-->
             netfs_begin_read()-->
               netfs_rreq_submit_slice()-->
                 netfs_read_from_server()-->
                   rreq->netfs_ops->issue_read()-->
                     ceph_netfs_issue_read()-->
                     {
                       ...
                       if (ci->i_inline_version != CEPH_INLINE_NONE &&
                           ceph_netfs_issue_op_inline(subreq))
                         return;
                       ...
                     }
     ceph_put_cap_refs(ci, Fwb);

The ceph_netfs_issue_op_inline() will send a getattr(Fsr) request to
mds.1.

4, then the mds.1 will request the rd lock for CInode::filelock from
the auth mds.0, the mds.0 will do the CInode::filelock state transation
from excl --> sync, but it need to revoke the Fxwb caps back from the
clients.

While the kernel client has aleady held the Fwb caps and waiting for
the getattr(Fsr).

It's deadlock!

URL: https://tracker.ceph.com/issues/55377
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
This commit is contained in:
Xiubo Li 2022-04-25 16:08:24 +08:00 committed by Ilya Dryomov
parent 3459bd0c55
commit 825978fd6a
1 changed files with 23 additions and 18 deletions
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41
fs/ceph/addr.c
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@ -1648,7 +1648,7 @@ int ceph_uninline_data(struct file *file)
struct inode *inode = file_inode(file);
struct ceph_inode_info *ci = ceph_inode(inode);
struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
struct ceph_osd_request *req;
struct ceph_osd_request *req = NULL;
struct ceph_cap_flush *prealloc_cf;
struct folio *folio = NULL;
u64 inline_version = CEPH_INLINE_NONE;
@ -1656,18 +1656,6 @@ int ceph_uninline_data(struct file *file)
int err = 0;
u64 len;
prealloc_cf = ceph_alloc_cap_flush();
if (!prealloc_cf)
return -ENOMEM;
folio = read_mapping_folio(inode->i_mapping, 0, file);
if (IS_ERR(folio)) {
err = PTR_ERR(folio);
goto out;
}
folio_lock(folio);
spin_lock(&ci->i_ceph_lock);
inline_version = ci->i_inline_version;
spin_unlock(&ci->i_ceph_lock);
@ -1675,9 +1663,23 @@ int ceph_uninline_data(struct file *file)
dout("uninline_data %p %llx.%llx inline_version %llu\n",
inode, ceph_vinop(inode), inline_version);
if (inline_version == 1 || /* initial version, no data */
inline_version == CEPH_INLINE_NONE)
goto out_unlock;
if (inline_version == CEPH_INLINE_NONE)
return 0;
prealloc_cf = ceph_alloc_cap_flush();
if (!prealloc_cf)
return -ENOMEM;
if (inline_version == 1) /* initial version, no data */
goto out_uninline;
folio = read_mapping_folio(inode->i_mapping, 0, file);
if (IS_ERR(folio)) {
err = PTR_ERR(folio);
goto out;
}
folio_lock(folio);
len = i_size_read(inode);
if (len > folio_size(folio))
@ -1743,6 +1745,7 @@ int ceph_uninline_data(struct file *file)
ceph_update_write_metrics(&fsc->mdsc->metric, req->r_start_latency,
req->r_end_latency, len, err);
out_uninline:
if (!err) {
int dirty;
@ -1761,8 +1764,10 @@ out_put_req:
if (err == -ECANCELED)
err = 0;
out_unlock:
folio_unlock(folio);
folio_put(folio);
if (folio) {
folio_unlock(folio);
folio_put(folio);
}
out:
ceph_free_cap_flush(prealloc_cf);
dout("uninline_data %p %llx.%llx inline_version %llu = %d\n",