fs: pass only I_DIRTY_INODE flags to ->dirty_inode

->dirty_inode is now only called when I_DIRTY_INODE (I_DIRTY_SYNC and/or
I_DIRTY_DATASYNC) is set.  However it may still be passed other dirty
flags at the same time, provided that these other flags happened to be
passed to __mark_inode_dirty() at the same time as I_DIRTY_INODE.

This doesn't make sense because there is no reason for filesystems to
care about these extra flags.  Nor are filesystems notified about all
updates to these other flags.

Therefore, mask the flags before passing them to ->dirty_inode.

Also properly document ->dirty_inode in vfs.rst.

Link: https://lore.kernel.org/r/20210112190253.64307-7-ebiggers@kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst
index ca52c82e5bb5494d0ac9721995226d63fc5cd012..287b80948a40b66935932febfcb4e2e3b50c25ed 100644 (file)
--- a/Documentation/filesystems/vfs.rst
+++ b/Documentation/filesystems/vfs.rst
@@ -270,7 +270,10 @@ or bottom half).
        ->alloc_inode.
 
 ``dirty_inode``
-       this method is called by the VFS to mark an inode dirty.
+       this method is called by the VFS when an inode is marked dirty.
+       This is specifically for the inode itself being marked dirty,
+       not its data.  If the update needs to be persisted by fdatasync(),
+       then I_DIRTY_DATASYNC will be set in the flags argument.
 
 ``write_inode``
        this method is called when the VFS needs to write an inode to

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index b7616bbd553360e5a2f1fc39c1abda57feafd0b6..2e6064012f7d399f86e1963c0e895fd5483f1bd8 100644 (file)
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -2259,7 +2259,7 @@ void __mark_inode_dirty(struct inode *inode, int flags)
                trace_writeback_dirty_inode_start(inode, flags);
 
                if (sb->s_op->dirty_inode)
-                       sb->s_op->dirty_inode(inode, flags);
+                       sb->s_op->dirty_inode(inode, flags & I_DIRTY_INODE);
 
                trace_writeback_dirty_inode(inode, flags);