bcache: add sysfs_strtoul_bool() for setting bit-field variables

When setting bool values via sysfs interface, e.g. writeback_metadata,
if writing 1 into writeback_metadata file, dc->writeback_metadata is
set to 1, but if writing 2 into the file, dc->writeback_metadata is
0. This is misleading, a better result should be 1 for all non-zero
input value.

It is because dc->writeback_metadata is a bit-field variable, and
current code simply use d_strtoul() to convert a string into integer
and takes the lowest bit value. To fix such error, we need a routine
to convert the input string into unsigned integer, and set target
variable to 1 if the converted integer is non-zero.

This patch introduces a new macro called sysfs_strtoul_bool(), it can
be used to convert input string into bool value, we can use it to set
bool value for bit-field vairables.

Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/md/bcache/sysfs.h b/drivers/md/bcache/sysfs.h
index 0ad2715a884e871de949f76af75dacb4c6d6b79e..215df32f567b9143c192cc2d67b63a5831b150e7 100644 (file)
--- a/drivers/md/bcache/sysfs.h
+++ b/drivers/md/bcache/sysfs.h
@@ -79,6 +79,16 @@ do {                                                                 \
                return strtoul_safe(buf, var) ?: (ssize_t) size;        \
 } while (0)
 
+#define sysfs_strtoul_bool(file, var)                                  \
+do {                                                                   \
+       if (attr == &sysfs_ ## file) {                                  \
+               unsigned long v = strtoul_or_return(buf);               \
+                                                                       \
+               var = v ? 1 : 0;                                        \
+               return size;                                            \
+       }                                                               \
+} while (0)
+
 #define sysfs_strtoul_clamp(file, var, min, max)                       \
 do {                                                                   \
        if (attr == &sysfs_ ## file) {                                  \