linux-kernel - [PATCH 2/3] afs: Fix getattr to report server i

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Message-Id: <20230502163528.1564398-3-dhowells@redhat.com>
Date:   Tue,  2 May 2023 17:35:27 +0100
From:   David Howells <dhowells@...hat.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     David Howells <dhowells@...hat.com>,
        Marc Dionne <marc.dionne@...istor.com>,
        linux-afs@...ts.infradead.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] afs: Fix getattr to report server i_size on dirs, not local size

Fix afs_getattr() to report the server's idea of the file size of a
directory rather than the local size.  The local size may differ as we edit
the local copy to avoid having to redownload it and we may end up with a
differently structured blob of a different size.

However, if the directory is discarded from the pagecache we then download
it again and the user may see the directory file size apparently change.

Fixes: 63a4681ff39c ("afs: Locally edit directory data for mkdir/create/unlink/...")
Signed-off-by: David Howells <dhowells@...hat.com>
cc: Marc Dionne <marc.dionne@...istor.com>
cc: linux-afs@...ts.infradead.org
---
 fs/afs/inode.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 82edd3351734..866bab860a88 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -450,7 +450,7 @@ static void afs_get_inode_cache(struct afs_vnode *vnode)
 				    0 : FSCACHE_ADV_SINGLE_CHUNK,
 				    &key, sizeof(key),
 				    &aux, sizeof(aux),
-				    vnode->status.size));
+				    i_size_read(&vnode->netfs.inode)));
 #endif
 }
 
@@ -777,6 +777,13 @@ int afs_getattr(struct mnt_idmap *idmap, const struct path *path,
 		if (test_bit(AFS_VNODE_SILLY_DELETED, &vnode->flags) &&
 		    stat->nlink > 0)
 			stat->nlink -= 1;
+
+		/* Lie about the size of directories.  We maintain a locally
+		 * edited copy and may make different allocation decisions on
+		 * it, but we need to give userspace the server's size.
+		 */
+		if (S_ISDIR(inode->i_mode))
+			stat->size = vnode->netfs.remote_i_size;
 	} while (need_seqretry(&vnode->cb_lock, seq));
 
 	done_seqretry(&vnode->cb_lock, seq);