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Specify ring blocks with index,nr

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Specifying the ring blocks with a head and tail index lead to pretty
confusing code to figure out how many blocks to read and if we had
passed the tail.

Instead specify the ring with a starting index and number of blocks.
The code to read and write the ring blocks naturally falls out and is a
lot more clear.

Signed-off-by: Zach Brown <zab@versity.com>
This commit is contained in:
Zach Brown
2016-12-08 11:19:43 -08:00
parent b598bf855d
commit f9ca1885f9
2 changed files with 29 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
kmod/src/format.h
View File

@@ -314,9 +314,9 @@ struct scoutfs_super_block {
__le64 free_blocks;
__le64 ring_blkno;
__le64 ring_blocks;
__le64 ring_head_index;
__le64 ring_tail_index;
__le64 ring_head_seq;
__le64 ring_index;
__le64 ring_nr;
__le64 ring_seq;
__le64 buddy_blocks;
struct scoutfs_buddy_root buddy_root;
struct scoutfs_btree_root btree_root;

65
kmod/src/ring.c
View File

@@ -116,10 +116,9 @@ int scoutfs_ring_submit_write(struct super_block *sb,
{
struct scoutfs_super_block *super = &SCOUTFS_SB(sb)->super;
DECLARE_RING_INFO(sb, rinf);
u64 first_blocks;
u64 head_blocks;
u64 first;
u64 last;
u64 wrapped_blocks;
u64 index_blocks;
u64 index;
if (!rinf->nr_blocks)
return 0;
@@ -128,30 +127,25 @@ int scoutfs_ring_submit_write(struct super_block *sb,
finish_block(rinf->ring, rinf->space);
/* first and last ring block indexes that will be written */
first = ring_ind_wrap(super, le64_to_cpu(super->ring_tail_index) + 1);
last = ring_ind_wrap(super, first + rinf->nr_blocks - 1);
index = ring_ind_wrap(super, le64_to_cpu(super->ring_index) +
le64_to_cpu(super->ring_nr));
index_blocks = min_t(u64, rinf->nr_blocks,
le64_to_cpu(super->ring_blocks) - index);
wrapped_blocks = rinf->nr_blocks - index_blocks;
/* number of blocks to write from first index and from head of ring */
first_blocks = min(last - first + 1,
le64_to_cpu(super->ring_blocks) - first);
if (last < first)
head_blocks = last + 1;
else
head_blocks = 0;
if (head_blocks) {
if (wrapped_blocks) {
BUILD_BUG_ON(SCOUTFS_BLOCK_SIZE != PAGE_SIZE);
scoutfs_bio_submit_comp(sb, WRITE, rinf->pages + first_blocks,
scoutfs_bio_submit_comp(sb, WRITE, rinf->pages + index_blocks,
le64_to_cpu(super->ring_blkno),
head_blocks, comp);
wrapped_blocks, comp);
}
scoutfs_bio_submit_comp(sb, WRITE, rinf->pages,
le64_to_cpu(super->ring_blkno) + first,
first_blocks, comp);
le64_to_cpu(super->ring_blkno) + index,
index_blocks, comp);
/* record new tail index in super and reset for next trans */
super->ring_tail_index = cpu_to_le64(last);
le64_add_cpu(&super->ring_nr, rinf->nr_blocks);
rinf->nr_blocks = 0;
rinf->space = 0;
@@ -232,10 +226,10 @@ int scoutfs_ring_read(struct super_block *sb)
struct page *page;
u64 index;
u64 blkno;
u64 tail;
u64 part;
u64 seq;
u64 nr;
int ret;
int nr;
int i;
/* nr_blocks/pages calc doesn't handle multiple pages per block */
@@ -255,20 +249,17 @@ int scoutfs_ring_read(struct super_block *sb)
pages[i] = page;
}
index = le64_to_cpu(super->ring_head_index);
tail = le64_to_cpu(super->ring_tail_index);
seq = le64_to_cpu(super->ring_head_seq);
index = le64_to_cpu(super->ring_index);
nr = le64_to_cpu(super->ring_nr);
seq = le64_to_cpu(super->ring_seq);
for(;;) {
while (nr) {
blkno = le64_to_cpu(super->ring_blkno) + index;
/* XXX min3_t should be a thing */
part = min3(nr, (u64)NR_BLOCKS,
le64_to_cpu(super->ring_blocks) - index);
if (index <= tail)
nr = tail - index + 1;
else
nr = le64_to_cpu(super->ring_blocks) - index;
nr = min_t(int, nr, NR_BLOCKS);
trace_printk("index %llu tail %llu nr %u\n", index, tail, nr);
trace_printk("index %llu nr %llu\n", index, nr);
ret = scoutfs_bio_read(sb, pages, blkno, nr);
if (ret)
@@ -283,12 +274,8 @@ int scoutfs_ring_read(struct super_block *sb)
goto out;
}
if (index == tail)
break;
index += nr;
if (index == le64_to_cpu(super->ring_blocks))
index = 0;
index = ring_ind_wrap(super, index + part);
nr -= part;
}
out: