From a3a6212c7d67baebebd0e4c2cf2ae1b75eb9231e Mon Sep 17 00:00:00 2001 From: Barret Rhoden Date: Thu, 2 Jul 2026 09:09:32 +0000 Subject: [PATCH] 9p: treat read return values of 0 as EOF If your 9p server shares a synthetic file system such as sysfs, the file size from stat often disagrees with the actual file size. Treat non-error reads of 0 as EOF, except in the case where the request was for 0 bytes. Tested: git@github.com:hugelgupf/p9.git, served "/" on 10.0.2.2 bash-5.3# mount -t 9p -o trans=tcp,port=12345,cache=none 10.0.2.2 /tmp/foo bash-5.3# cat /tmp/foo/sys/devices/system/cpu/online 0-47 Fixes: eb497943fa21 ("9p: Convert to using the netfs helper lib to do reads and caching") Signed-off-by: Barret Rhoden Message-ID: <20260702090941.1298188-1-brho@google.com> Signed-off-by: Dominique Martinet --- fs/9p/vfs_addr.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c index 33da8140572e..65eea22919b9 100644 --- a/fs/9p/vfs_addr.c +++ b/fs/9p/vfs_addr.c @@ -99,6 +99,7 @@ static void v9fs_issue_read(struct netfs_io_subrequest *subreq) char *target; unsigned long long pos = subreq->start + subreq->transferred; int total = 0, err, len, n; + size_t to_read = iov_iter_count(&subreq->io_iter); if (S_ISLNK(rreq->inode->i_mode)) { /* p9_client_readlink() must not be called for legacy protocols @@ -131,6 +132,8 @@ static void v9fs_issue_read(struct netfs_io_subrequest *subreq) __set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags); if (pos + total >= i_size_read(rreq->inode)) __set_bit(NETFS_SREQ_HIT_EOF, &subreq->flags); + if (!err && !total && to_read) + __set_bit(NETFS_SREQ_HIT_EOF, &subreq->flags); if (!err && total) { subreq->transferred += total; __set_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);