From: Song Liu <songliubraving@xxxxxx>
Next patches will use a disk as raid5/6 caching. We need a new disk role
to present the cache device and add MD_FEATURE_WRITE_CACHE to
feature_map for backward compability.
Signed-off-by: Song Liu <songliubraving@xxxxxx>
Signed-off-by: Shaohua Li <shli@xxxxxx>
---
drivers/md/md.c | 24 ++++++++++++++++++++++--
drivers/md/md.h | 4 ++++
include/uapi/linux/raid/md_p.h | 3 +++
3 files changed, 29 insertions(+), 2 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 4dbed4a..599525c 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1656,6 +1656,16 @@ static int super_1_validate(struct mddev *mddev, struct md_rdev *rdev)
case 0xfffe: /* faulty */
set_bit(Faulty, &rdev->flags);
break;
+ case 0xfffd: /* cache device */
+ if (!(sb->feature_map & MD_FEATURE_WRITE_CACHE)) {
+ /* cache device without cache feature */
+ printk(KERN_WARNING
+ "md: cache device provided without write "
+ "cache feature, ignoring the device\n");
+ return -EINVAL;
+ }
+ set_bit(WriteCache, &rdev->flags);
+ break;
default:
rdev->saved_raid_disk = role;
if ((le32_to_cpu(sb->feature_map) &
@@ -1811,7 +1821,10 @@ static void super_1_sync(struct mddev *mddev, struct md_rdev *rdev)
sb->dev_roles[i] = cpu_to_le16(0xfffe);
else if (test_bit(In_sync, &rdev2->flags))
sb->dev_roles[i] = cpu_to_le16(rdev2->raid_disk);
- else if (rdev2->raid_disk >= 0)
+ else if (test_bit(WriteCache, &rdev2->flags)) {
+ sb->dev_roles[i] = cpu_to_le16(0xfffd);
+ sb->feature_map |= cpu_to_le32(MD_FEATURE_WRITE_CACHE);
+ } else if (rdev2->raid_disk >= 0)
sb->dev_roles[i] = cpu_to_le16(rdev2->raid_disk);
else
sb->dev_roles[i] = cpu_to_le16(0xffff);
@@ -5781,7 +5794,8 @@ static int get_disk_info(struct mddev *mddev, void __user * arg)
else if (test_bit(In_sync, &rdev->flags)) {
info.state |= (1<<MD_DISK_ACTIVE);
info.state |= (1<<MD_DISK_SYNC);
- }
+ } else if (test_bit(WriteCache, &rdev->flags))
+ info.state |= (1<<MD_DISK_WRITECACHE);
if (test_bit(WriteMostly, &rdev->flags))
info.state |= (1<<MD_DISK_WRITEMOSTLY);
} else {
@@ -5896,6 +5910,8 @@ static int add_new_disk(struct mddev *mddev, mdu_disk_info_t *info)
else
clear_bit(WriteMostly, &rdev->flags);
+ if (info->state & (1<<MD_DISK_WRITECACHE))
+ set_bit(WriteCache, &rdev->flags);
/*
* check whether the device shows up in other nodes
*/
@@ -7264,6 +7280,10 @@ static int md_seq_show(struct seq_file *seq, void *v)
seq_printf(seq, "(F)");
continue;
}
+ if (test_bit(WriteCache, &rdev->flags)) {
+ seq_printf(seq, "(C)");
+ continue;
+ }
if (rdev->raid_disk < 0)
seq_printf(seq, "(S)"); /* spare */
if (test_bit(Replacement, &rdev->flags))
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 4046a6c..6857592 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -175,6 +175,10 @@ enum flag_bits {
* This device is seen locally but not
* by the whole cluster
*/
+ WriteCache, /* This device is used as write cache.
+ * Usually, this device should be faster
+ * than other devices in the array
+ */
};
#define BB_LEN_MASK (0x00000000000001FFULL)
diff --git a/include/uapi/linux/raid/md_p.h b/include/uapi/linux/raid/md_p.h
index 2ae6131..8c8e12c 100644
--- a/include/uapi/linux/raid/md_p.h
+++ b/include/uapi/linux/raid/md_p.h
@@ -89,6 +89,7 @@
* read requests will only be sent here in
* dire need
*/
+#define MD_DISK_WRITECACHE 18 /* disk is used as the write cache in RAID-5/6 */
typedef struct mdp_device_descriptor_s {
__u32 number; /* 0 Device number in the entire set */
@@ -302,6 +303,7 @@ struct mdp_superblock_1 {
#define MD_FEATURE_RECOVERY_BITMAP 128 /* recovery that is happening
* is guided by bitmap.
*/
+#define MD_FEATURE_WRITE_CACHE 256 /* support write cache */
#define MD_FEATURE_ALL (MD_FEATURE_BITMAP_OFFSET \
|MD_FEATURE_RECOVERY_OFFSET \
|MD_FEATURE_RESHAPE_ACTIVE \
@@ -310,6 +312,7 @@ struct mdp_superblock_1 {
|MD_FEATURE_RESHAPE_BACKWARDS \
|MD_FEATURE_NEW_OFFSET \
|MD_FEATURE_RECOVERY_BITMAP \
+ |MD_FEATURE_WRITE_CACHE \
)
#endif
--
1.8.1
--
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