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toninov 2025-10-12 19:21:47 +02:00
parent 1bf6e3c6aa
commit 57cd2d2850
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1 changed files with 15 additions and 5 deletions
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20
docs/locking.md
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@ -60,7 +60,8 @@ The lock is then re-acquired at the end, once the CWBs return, to effectively ma
Let us start with the FLUSH handler, and its helper functions:
```rust
fn flush():
fn flush()
{
RWSEM.down_write();
// Populate the FLUSH state, while we are holding the locks
err = prepare_cwbs();
@ -83,10 +84,12 @@ fn flush():
RWSEM.up_write();
return err;
}
// Under rwsem
fn prepare_cwbs():
fn prepare_cwbs()
{
for_each_set_bit(DIRTY, block)
first_lsi = block*1024;
last_lsi = first_lsi + 1024;
@ -97,10 +100,12 @@ fn prepare_cwbs():
// At the end, the whole SNAP_SEQNUM is equal to SEQNUM and
// the whole FLUSH_PENDING is equal to DIRTY.
return;
}
// No lock
fn send_cwbs():
fn send_cwbs()
{
// Completion of all callbacks
atomic_t pending = 1;
struct completion compl;
@ -121,10 +126,12 @@ fn send_cwbs():
wait_for_completion(compl);
return err;
}
// Async callback of CWB
fn cwb_callback(err, ctx):
fn cwb_callback(err, ctx)
{
if (err)
// Many callbacks could be executing concurrently
spin_lock(CWB_ERROR_LOCK);
@ -135,10 +142,12 @@ fn cwb_callback(err, ctx):
complete(ctx.compl);
return;
}
// Under rwsem again
fn mark_blocks_clean():
fn mark_blocks_clean()
{
err = false;
for_each_set_bit(FLUSH_PENDING, block)
@ -150,6 +159,7 @@ fn mark_blocks_clean():
// Only return err = false if no CWB failed
return err;
}
```
A few things to notice: