From 8ddf9efe6708f3674f0ddfeb6425fd27bea109a2 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Fri, 9 Sep 2005 16:23:45 -0700 Subject: [PATCH] md: support write-mostly device in raid1 This allows a device in a raid1 to be marked as "write mostly". Read requests will only be sent if there is no other option. Signed-off-by: Neil Brown Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/raid/md_p.h | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'include/linux/raid/md_p.h') diff --git a/include/linux/raid/md_p.h b/include/linux/raid/md_p.h index dc65cd43549..4f047f84fb1 100644 --- a/include/linux/raid/md_p.h +++ b/include/linux/raid/md_p.h @@ -79,6 +79,11 @@ #define MD_DISK_SYNC 2 /* disk is in sync with the raid set */ #define MD_DISK_REMOVED 3 /* disk is in sync with the raid set */ +#define MD_DISK_WRITEMOSTLY 9 /* disk is "write-mostly" is RAID1 config. + * read requests will only be sent here in + * dire need + */ + typedef struct mdp_device_descriptor_s { __u32 number; /* 0 Device number in the entire set */ __u32 major; /* 1 Device major number */ @@ -193,7 +198,7 @@ struct mdp_superblock_1 { __u64 ctime; /* lo 40 bits are seconds, top 24 are microseconds or 0*/ __u32 level; /* -4 (multipath), -1 (linear), 0,1,4,5 */ - __u32 layout; /* only for raid5 currently */ + __u32 layout; /* only for raid5 and raid10 currently */ __u64 size; /* used size of component devices, in 512byte sectors */ __u32 chunksize; /* in 512byte sectors */ @@ -212,7 +217,9 @@ struct mdp_superblock_1 { __u32 dev_number; /* permanent identifier of this device - not role in raid */ __u32 cnt_corrected_read; /* number of read errors that were corrected by re-writing */ __u8 device_uuid[16]; /* user-space setable, ignored by kernel */ - __u8 pad2[64-56]; /* set to 0 when writing */ + __u8 devflags; /* per-device flags. Only one defined...*/ +#define WriteMostly1 1 /* mask for writemostly flag in above */ + __u8 pad2[64-57]; /* set to 0 when writing */ /* array state information - 64 bytes */ __u64 utime; /* 40 bits second, 24 btes microseconds */ -- cgit v1.2.3