Patch "ceph: request Fw caps before updating the mtime in ceph_write_iter" has been added to the 5.14-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    ceph: request Fw caps before updating the mtime in ceph_write_iter

to the 5.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ceph-request-fw-caps-before-updating-the-mtime-in-ce.patch
and it can be found in the queue-5.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit fa60ee4c50be3d6bfd05824790fd8a83976361af
Author: Jeff Layton <jlayton@xxxxxxxxxx>
Date:   Wed Aug 11 06:40:42 2021 -0400

    ceph: request Fw caps before updating the mtime in ceph_write_iter
    
    [ Upstream commit b11ed50346683a749632ea664959b28d524d7395 ]
    
    The current code will update the mtime and then try to get caps to
    handle the write. If we end up having to request caps from the MDS, then
    the mtime in the cap grant will clobber the updated mtime and it'll be
    lost.
    
    This is most noticable when two clients are alternately writing to the
    same file. Fw caps are continually being granted and revoked, and the
    mtime ends up stuck because the updated mtimes are always being
    overwritten with the old one.
    
    Fix this by changing the order of operations in ceph_write_iter to get
    the caps before updating the times. Also, make sure we check the pool
    full conditions before even getting any caps or uninlining.
    
    URL: https://tracker.ceph.com/issues/46574
    Reported-by: Jozef Kováč <kovac@xxxxxxxxxxxxxxx>
    Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
    Reviewed-by: Xiubo Li <xiubli@xxxxxxxxxx>
    Reviewed-by: Luis Henriques <lhenriques@xxxxxxx>
    Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index d1755ac1d964..3daebfaec8c6 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -1722,32 +1722,26 @@ retry_snap:
 		goto out;
 	}
 
-	err = file_remove_privs(file);
-	if (err)
+	down_read(&osdc->lock);
+	map_flags = osdc->osdmap->flags;
+	pool_flags = ceph_pg_pool_flags(osdc->osdmap, ci->i_layout.pool_id);
+	up_read(&osdc->lock);
+	if ((map_flags & CEPH_OSDMAP_FULL) ||
+	    (pool_flags & CEPH_POOL_FLAG_FULL)) {
+		err = -ENOSPC;
 		goto out;
+	}
 
-	err = file_update_time(file);
+	err = file_remove_privs(file);
 	if (err)
 		goto out;
 
-	inode_inc_iversion_raw(inode);
-
 	if (ci->i_inline_version != CEPH_INLINE_NONE) {
 		err = ceph_uninline_data(file, NULL);
 		if (err < 0)
 			goto out;
 	}
 
-	down_read(&osdc->lock);
-	map_flags = osdc->osdmap->flags;
-	pool_flags = ceph_pg_pool_flags(osdc->osdmap, ci->i_layout.pool_id);
-	up_read(&osdc->lock);
-	if ((map_flags & CEPH_OSDMAP_FULL) ||
-	    (pool_flags & CEPH_POOL_FLAG_FULL)) {
-		err = -ENOSPC;
-		goto out;
-	}
-
 	dout("aio_write %p %llx.%llx %llu~%zd getting caps. i_size %llu\n",
 	     inode, ceph_vinop(inode), pos, count, i_size_read(inode));
 	if (fi->fmode & CEPH_FILE_MODE_LAZY)
@@ -1759,6 +1753,12 @@ retry_snap:
 	if (err < 0)
 		goto out;
 
+	err = file_update_time(file);
+	if (err)
+		goto out_caps;
+
+	inode_inc_iversion_raw(inode);
+
 	dout("aio_write %p %llx.%llx %llu~%zd got cap refs on %s\n",
 	     inode, ceph_vinop(inode), pos, count, ceph_cap_string(got));
 
@@ -1842,6 +1842,8 @@ retry_snap:
 	}
 
 	goto out_unlocked;
+out_caps:
+	ceph_put_cap_refs(ci, got);
 out:
 	if (direct_lock)
 		ceph_end_io_direct(inode);