ext4: wire up the "new_write" option
For debugging purposes, the new_write mount option will enable the
ext4 write codepath. This will allow us to compare the old and new
write paths from a stability and benchmarking perspective.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 140e1eb..408980a 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1267,6 +1267,9 @@ struct ext4_inode_info {
#define EXT4_MOUNT2_MB_OPTIMIZE_SCAN 0x00000080 /* Optimize group
* scanning in mballoc
*/
+#define EXT4_MOUNT2_NEW_WRITE 0x00000100 /* New write path to replace
+ dioread_nolock and
+ nodioread_nolock */
#define clear_opt(sb, opt) EXT4_SB(sb)->s_mount_opt &= \
~EXT4_MOUNT_##opt
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 72ead3b..1227e0c 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1591,6 +1591,7 @@ enum {
Opt_max_dir_size_kb, Opt_nojournal_checksum, Opt_nombcache,
Opt_no_prefetch_block_bitmaps, Opt_mb_optimize_scan,
Opt_errors, Opt_data, Opt_data_err, Opt_jqfmt, Opt_dax_type,
+ Opt_new_write,
#ifdef CONFIG_EXT4_DEBUG
Opt_fc_debug_max_replay, Opt_fc_debug_force
#endif
@@ -1731,6 +1732,7 @@ static const struct fs_parameter_spec ext4_param_specs[] = {
Opt_removed),
fsparam_flag ("no_prefetch_block_bitmaps",
Opt_no_prefetch_block_bitmaps),
+ fsparam_flag ("new_write", Opt_new_write),
fsparam_s32 ("mb_optimize_scan", Opt_mb_optimize_scan),
fsparam_string ("check", Opt_removed), /* mount option from ext2/3 */
fsparam_flag ("nocheck", Opt_removed), /* mount option from ext2/3 */
@@ -1830,6 +1832,7 @@ static const struct mount_opts {
{Opt_fc_debug_force, EXT4_MOUNT2_JOURNAL_FAST_COMMIT,
MOPT_SET | MOPT_2 | MOPT_EXT4_ONLY},
#endif
+ {Opt_new_write, EXT4_MOUNT2_NEW_WRITE, MOPT_SET | MOPT_2 },
{Opt_err, 0, 0}
};
@@ -2978,6 +2981,8 @@ static int _ext4_show_options(struct seq_file *seq, struct super_block *sb,
} else if (test_opt2(sb, DAX_INODE)) {
SEQ_OPTS_PUTS("dax=inode");
}
+ if (test_opt2(sb, NEW_WRITE))
+ SEQ_OPTS_PUTS("new_write");
if (sbi->s_groups_count >= MB_DEFAULT_LINEAR_SCAN_THRESHOLD &&
!test_opt2(sb, MB_OPTIMIZE_SCAN)) {
