From: Jan Glauber jglauber@digitalocean.com
stable inclusion from linux-4.19.191 commit bc1355f10b2acddee56680f567edaa0e4a18db44
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commit 7abfabaf5f805f5171d133ce6af9b65ab766e76a upstream.
Reading /proc/mdstat with a read buffer size that would not fit the unused status line in the first read will skip this line from the output.
So 'dd if=/proc/mdstat bs=64 2>/dev/null' will not print something like: unused devices: <none>
Don't return NULL immediately in start() for v=2 but call show() once to print the status line also for multiple reads.
Cc: stable@vger.kernel.org Fixes: 1f4aace60b0e ("fs/seq_file.c: simplify seq_file iteration code and interface") Signed-off-by: Jan Glauber jglauber@digitalocean.com Signed-off-by: Song Liu songliubraving@fb.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- drivers/md/md.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c index 4045aa6103367..c8f26788c3da5 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -7883,7 +7883,11 @@ static void *md_seq_start(struct seq_file *seq, loff_t *pos) loff_t l = *pos; struct mddev *mddev;
- if (l >= 0x10000) + if (l == 0x10000) { + ++*pos; + return (void *)2; + } + if (l > 0x10000) return NULL; if (!l--) /* header */