In lieu of get_seq_buf + seq_commit, provide a way to "undo" writes if
we use seq_printf
Fixes: 252c651a4c85 ("blk-cgroup: stop using seq_get_buf")
Signed-off-by: Khazhismel Kumykov <khazhy@xxxxxxxxxx>
---
block/blk-cgroup.c | 5 +++++
fs/seq_file.c | 14 ++++++++++++++
include/linux/seq_file.h | 2 ++
3 files changed, 21 insertions(+)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 8dfe62786cd5..50043a742c48 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -909,6 +909,7 @@ static void blkcg_print_one_stat(struct blkcg_gq *blkg, struct seq_file *s)
const char *dname;
unsigned seq;
int i;
+ int scookie;
if (!blkg->online)
return;
@@ -917,6 +918,8 @@ static void blkcg_print_one_stat(struct blkcg_gq *blkg, struct seq_file *s)
if (!dname)
return;
+ scookie = seq_checkpoint(s);
+
seq_printf(s, "%s ", dname);
do {
@@ -956,6 +959,8 @@ static void blkcg_print_one_stat(struct blkcg_gq *blkg, struct seq_file *s)
if (has_stats)
seq_printf(s, "\n");
+ else
+ seq_restore(s, scookie);
}
static int blkcg_print_stat(struct seq_file *sf, void *v)
diff --git a/fs/seq_file.c b/fs/seq_file.c
index 7ab8a58c29b6..c3ec6b57334e 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -408,6 +408,20 @@ void seq_printf(struct seq_file *m, const char *f, ...)
}
EXPORT_SYMBOL(seq_printf);
+int seq_checkpoint(struct seq_file *m)
+{
+ return m->count;
+}
+EXPORT_SYMBOL(seq_checkpoint);
+
+void seq_restore(struct seq_file *m, int count)
+{
+ if (WARN_ON_ONCE(count > m->count || count > m->size))
+ return;
+ m->count = count;
+}
+EXPORT_SYMBOL(seq_restore);
+
#ifdef CONFIG_BINARY_PRINTF
void seq_bprintf(struct seq_file *m, const char *f, const u32 *binary)
{
diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h
index 60820ab511d2..d3a05f7c2750 100644
--- a/include/linux/seq_file.h
+++ b/include/linux/seq_file.h
@@ -117,6 +117,8 @@ __printf(2, 0)
void seq_vprintf(struct seq_file *m, const char *fmt, va_list args);
__printf(2, 3)
void seq_printf(struct seq_file *m, const char *fmt, ...);
+int seq_checkpoint(struct seq_file *m);
+void seq_restore(struct seq_file *m, int count);
void seq_putc(struct seq_file *m, char c);
void seq_puts(struct seq_file *m, const char *s);
void seq_put_decimal_ull_width(struct seq_file *m, const char *delimiter,
--
2.36.0.550.gb090851708-goog
