Commit 1a8e9cf4 authored Jan 23, 2020 by Vasily Averin Committed by Theodore Ts'o Jan 25, 2020

jbd2_seq_info_next should increase position index

if seq_file .next fuction does not change position index,
read after some lseek can generate unexpected output.

Script below generates endless output
 $ q=;while read -r r;do echo "$((++q)) $r";done </proc/fs/jbd2/DEV/info

https://bugzilla.kernel.org/show_bug.cgi?id=206283



Fixes: 1f4aace6 ("fs/seq_file.c: simplify seq_file iteration code and interface")
Cc: stable@kernel.org
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/d13805e5-695e-8ac3-b678-26ca2313629f@virtuozzo.com


Signed-off-by: Theodore Ts'o <tytso@mit.edu>

parent 17c51d83

fs/jbd2/journal.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -982,6 +982,7 @@ static void jbd2_seq_info_start(struct seq_file seq, loff_t *pos)

		static void jbd2_seq_info_next(struct seq_file seq, void v, loff_t pos)
		{
		(*pos)++;
		return NULL;
		}

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