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Add stale block read retrying helper

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Many readers had little implementations of the logic to decide to retry
stale reads with different refs or decide that they're persistent and
return hard errors.  Let's move that into a small helper.

Signed-off-by: Zach Brown <zab@versity.com>
This commit is contained in:
Zach Brown
2022-12-12 10:36:35 -08:00
parent 342c206550
commit 464de56d28
2 changed files with 41 additions and 0 deletions
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30
kmod/src/block.c
View File

@@ -728,6 +728,36 @@ out:
return ret;
}
static bool stale_refs_match(struct scoutfs_block_ref *caller, struct scoutfs_block_ref *saved)
{
return !caller || (caller->blkno == saved->blkno && caller->seq == saved->seq);
}
/*
* Check if a read of a reference that gave ESTALE should be retried or
* should generate a hard error. If this is the second time we got
* ESTALE from the same refs then we return EIO and the caller should
* stop. As long as we keep seeing different refs we'll return ESTALE
* and the caller can keep trying.
*/
int scoutfs_block_check_stale(struct super_block *sb, int ret,
struct scoutfs_block_saved_refs *saved,
struct scoutfs_block_ref *a, struct scoutfs_block_ref *b)
{
if (ret == -ESTALE) {
if (stale_refs_match(a, &saved->refs[0]) && stale_refs_match(b, &saved->refs[1])){
ret = -EIO;
} else {
if (a)
saved->refs[0] = *a;
if (b)
saved->refs[1] = *b;
}
}
return ret;
}
void scoutfs_block_put(struct super_block *sb, struct scoutfs_block *bl)
{
if (!IS_ERR_OR_NULL(bl))

11
kmod/src/block.h
View File

@@ -13,6 +13,17 @@ struct scoutfs_block {
void *priv;
};
struct scoutfs_block_saved_refs {
struct scoutfs_block_ref refs[2];
};
#define DECLARE_SAVED_REFS(name) \
struct scoutfs_block_saved_refs name = {{{0,}}}
int scoutfs_block_check_stale(struct super_block *sb, int ret,
struct scoutfs_block_saved_refs *saved,
struct scoutfs_block_ref *a, struct scoutfs_block_ref *b);
int scoutfs_block_read_ref(struct super_block *sb, struct scoutfs_block_ref *ref, u32 magic,
struct scoutfs_block **bl_ret);
void scoutfs_block_put(struct super_block *sb, struct scoutfs_block *bl);