Btrfs: RAID5 and RAID6
This builds on David Woodhouse's original Btrfs raid5/6 implementation.
The code has changed quite a bit, blame Chris Mason for any bugs.
Read/modify/write is done after the higher levels of the filesystem have
prepared a given bio. This means the higher layers are not responsible
for building full stripes, and they don't need to query for the topology
of the extents that may get allocated during delayed allocation runs.
It also means different files can easily share the same stripe.
But, it does expose us to incorrect parity if we crash or lose power
while doing a read/modify/write cycle. This will be addressed in a
later commit.
Scrub is unable to repair crc errors on raid5/6 chunks.
Discard does not work on raid5/6 (yet)
The stripe size is fixed at 64KiB per disk. This will be tunable
in a later commit.
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index d133edf..3345f68 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -31,6 +31,7 @@
#include "print-tree.h"
#include "transaction.h"
#include "volumes.h"
+#include "raid56.h"
#include "locking.h"
#include "free-space-cache.h"
#include "math.h"
@@ -1852,6 +1853,8 @@
*actual_bytes = discarded_bytes;
+ if (ret == -EOPNOTSUPP)
+ ret = 0;
return ret;
}
@@ -3276,6 +3279,7 @@
u64 num_devices = root->fs_info->fs_devices->rw_devices +
root->fs_info->fs_devices->missing_devices;
u64 target;
+ u64 tmp;
/*
* see if restripe for this chunk_type is in progress, if so
@@ -3292,30 +3296,32 @@
}
spin_unlock(&root->fs_info->balance_lock);
+ /* First, mask out the RAID levels which aren't possible */
if (num_devices == 1)
- flags &= ~(BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_RAID0);
+ flags &= ~(BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_RAID0 |
+ BTRFS_BLOCK_GROUP_RAID5);
+ if (num_devices < 3)
+ flags &= ~BTRFS_BLOCK_GROUP_RAID6;
if (num_devices < 4)
flags &= ~BTRFS_BLOCK_GROUP_RAID10;
- if ((flags & BTRFS_BLOCK_GROUP_DUP) &&
- (flags & (BTRFS_BLOCK_GROUP_RAID1 |
- BTRFS_BLOCK_GROUP_RAID10))) {
- flags &= ~BTRFS_BLOCK_GROUP_DUP;
- }
+ tmp = flags & (BTRFS_BLOCK_GROUP_DUP | BTRFS_BLOCK_GROUP_RAID0 |
+ BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_RAID5 |
+ BTRFS_BLOCK_GROUP_RAID6 | BTRFS_BLOCK_GROUP_RAID10);
+ flags &= ~tmp;
- if ((flags & BTRFS_BLOCK_GROUP_RAID1) &&
- (flags & BTRFS_BLOCK_GROUP_RAID10)) {
- flags &= ~BTRFS_BLOCK_GROUP_RAID1;
- }
+ if (tmp & BTRFS_BLOCK_GROUP_RAID6)
+ tmp = BTRFS_BLOCK_GROUP_RAID6;
+ else if (tmp & BTRFS_BLOCK_GROUP_RAID5)
+ tmp = BTRFS_BLOCK_GROUP_RAID5;
+ else if (tmp & BTRFS_BLOCK_GROUP_RAID10)
+ tmp = BTRFS_BLOCK_GROUP_RAID10;
+ else if (tmp & BTRFS_BLOCK_GROUP_RAID1)
+ tmp = BTRFS_BLOCK_GROUP_RAID1;
+ else if (tmp & BTRFS_BLOCK_GROUP_RAID0)
+ tmp = BTRFS_BLOCK_GROUP_RAID0;
- if ((flags & BTRFS_BLOCK_GROUP_RAID0) &&
- ((flags & BTRFS_BLOCK_GROUP_RAID1) |
- (flags & BTRFS_BLOCK_GROUP_RAID10) |
- (flags & BTRFS_BLOCK_GROUP_DUP))) {
- flags &= ~BTRFS_BLOCK_GROUP_RAID0;
- }
-
- return extended_to_chunk(flags);
+ return extended_to_chunk(flags | tmp);
}
static u64 get_alloc_profile(struct btrfs_root *root, u64 flags)
@@ -3333,6 +3339,7 @@
u64 btrfs_get_alloc_profile(struct btrfs_root *root, int data)
{
u64 flags;
+ u64 ret;
if (data)
flags = BTRFS_BLOCK_GROUP_DATA;
@@ -3341,7 +3348,8 @@
else
flags = BTRFS_BLOCK_GROUP_METADATA;
- return get_alloc_profile(root, flags);
+ ret = get_alloc_profile(root, flags);
+ return ret;
}
/*
@@ -3516,8 +3524,10 @@
{
u64 num_dev;
- if (type & BTRFS_BLOCK_GROUP_RAID10 ||
- type & BTRFS_BLOCK_GROUP_RAID0)
+ if (type & (BTRFS_BLOCK_GROUP_RAID10 |
+ BTRFS_BLOCK_GROUP_RAID0 |
+ BTRFS_BLOCK_GROUP_RAID5 |
+ BTRFS_BLOCK_GROUP_RAID6))
num_dev = root->fs_info->fs_devices->rw_devices;
else if (type & BTRFS_BLOCK_GROUP_RAID1)
num_dev = 2;
@@ -3667,7 +3677,9 @@
/*
* If we have dup, raid1 or raid10 then only half of the free
- * space is actually useable.
+ * space is actually useable. For raid56, the space info used
+ * doesn't include the parity drive, so we don't have to
+ * change the math
*/
if (profile & (BTRFS_BLOCK_GROUP_DUP |
BTRFS_BLOCK_GROUP_RAID1 |
@@ -5455,10 +5467,14 @@
return ret;
}
-static u64 stripe_align(struct btrfs_root *root, u64 val)
+static u64 stripe_align(struct btrfs_root *root,
+ struct btrfs_block_group_cache *cache,
+ u64 val, u64 num_bytes)
{
- u64 mask = ((u64)root->stripesize - 1);
- u64 ret = (val + mask) & ~mask;
+ u64 mask;
+ u64 ret;
+ mask = ((u64)root->stripesize - 1);
+ ret = (val + mask) & ~mask;
return ret;
}
@@ -5519,9 +5535,12 @@
index = 2;
else if (flags & BTRFS_BLOCK_GROUP_RAID0)
index = 3;
+ else if (flags & BTRFS_BLOCK_GROUP_RAID5)
+ index = 5;
+ else if (flags & BTRFS_BLOCK_GROUP_RAID6)
+ index = 6;
else
- index = 4;
-
+ index = 4; /* BTRFS_BLOCK_GROUP_SINGLE */
return index;
}
@@ -5665,6 +5684,8 @@
if (!block_group_bits(block_group, data)) {
u64 extra = BTRFS_BLOCK_GROUP_DUP |
BTRFS_BLOCK_GROUP_RAID1 |
+ BTRFS_BLOCK_GROUP_RAID5 |
+ BTRFS_BLOCK_GROUP_RAID6 |
BTRFS_BLOCK_GROUP_RAID10;
/*
@@ -5835,7 +5856,8 @@
goto loop;
}
checks:
- search_start = stripe_align(root, offset);
+ search_start = stripe_align(root, used_block_group,
+ offset, num_bytes);
/* move on to the next group */
if (search_start + num_bytes >
@@ -7203,6 +7225,7 @@
root->fs_info->fs_devices->missing_devices;
stripped = BTRFS_BLOCK_GROUP_RAID0 |
+ BTRFS_BLOCK_GROUP_RAID5 | BTRFS_BLOCK_GROUP_RAID6 |
BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_RAID10;
if (num_devices == 1) {
@@ -7754,7 +7777,9 @@
btrfs_release_path(path);
cache->flags = btrfs_block_group_flags(&cache->item);
cache->sectorsize = root->sectorsize;
-
+ cache->full_stripe_len = btrfs_full_stripe_len(root,
+ &root->fs_info->mapping_tree,
+ found_key.objectid);
btrfs_init_free_space_ctl(cache);
/*
@@ -7808,6 +7833,8 @@
if (!(get_alloc_profile(root, space_info->flags) &
(BTRFS_BLOCK_GROUP_RAID10 |
BTRFS_BLOCK_GROUP_RAID1 |
+ BTRFS_BLOCK_GROUP_RAID5 |
+ BTRFS_BLOCK_GROUP_RAID6 |
BTRFS_BLOCK_GROUP_DUP)))
continue;
/*
@@ -7883,6 +7910,9 @@
cache->key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
cache->sectorsize = root->sectorsize;
cache->fs_info = root->fs_info;
+ cache->full_stripe_len = btrfs_full_stripe_len(root,
+ &root->fs_info->mapping_tree,
+ chunk_offset);
atomic_set(&cache->count, 1);
spin_lock_init(&cache->lock);
