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scoutfs: fix final overlapping item/val

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Item headers are written from the front of the block to the tail.
Item values are written from the tail of the block towards the head.

The math to detect their overlapping in the center forgot to take the
length of the item header into account.  We could have final item
headers and values overriding each other which causes file data to
appear as an item header.

Signed-off-by: Zach Brown <zab@versity.com>
This commit is contained in:
Zach Brown
2016-03-29 11:25:36 -07:00
parent c7c8969704
commit 97e6c1e605
1 changed files with 8 additions and 2 deletions
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10
kmod/src/segment.c
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@@ -201,6 +201,12 @@ int scoutfs_read_item(struct super_block *sb, struct scoutfs_key *key,
return ret;
}
/* return the byte length of the item header including its skip elements */
static int item_bytes(int height)
{
return offsetof(struct scoutfs_item, skip_next[height]);
}
/*
* The dirty_item_off points to the byte offset after the last item.
* Advance it past block tails and initial block headers until there's
@@ -209,7 +215,7 @@ int scoutfs_read_item(struct super_block *sb, struct scoutfs_key *key,
*/
static int add_item_off(struct scoutfs_sb_info *sbi, int height)
{
int len = offsetof(struct scoutfs_item, skip_next[height]);
int len = item_bytes(height);
int off = sbi->dirty_item_off;
int block_off;
int tail_free;
@@ -487,7 +493,7 @@ next_chunk:
trace_printk("item_off %u val_off %u\n", item_off, val_off);
if (item_off > val_off) {
if (item_off + item_bytes(height) > val_off) {
ret = finish_dirty_segment(sb);
if (ret)
goto out;