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NFS: Use wait_on_atomic_t() for unlock after readahead

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The use of wait_on_atomic_t() for waiting on I/O to complete before
unlocking allows us to git rid of the NFS_IO_INPROGRESS flag, and thus the
nfs_iocounter's flags member, and finally the nfs_iocounter altogether.
The count of I/O is moved to the lock context, and the counter
increment/decrement functions become simple enough to open-code.

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
[Trond: Fix up conflict with existing function nfs_wait_atomic_killable()]
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This commit is contained in:
Benjamin Coddington
2016-01-06 10:40:18 -05:00
committed by Trond Myklebust
parent 942e3d72a6
commit 210c7c1750
6 changed files with 23 additions and 70 deletions
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48
fs/nfs/pagelist.c
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@@ -101,53 +101,18 @@ nfs_page_free(struct nfs_page *p)
kmem_cache_free(nfs_page_cachep, p);
}
static void
nfs_iocounter_inc(struct nfs_io_counter *c)
{
atomic_inc(&c->io_count);
}
static void
nfs_iocounter_dec(struct nfs_io_counter *c)
{
if (atomic_dec_and_test(&c->io_count)) {
clear_bit(NFS_IO_INPROGRESS, &c->flags);
smp_mb__after_atomic();
wake_up_bit(&c->flags, NFS_IO_INPROGRESS);
}
}
static int
__nfs_iocounter_wait(struct nfs_io_counter *c)
{
wait_queue_head_t *wq = bit_waitqueue(&c->flags, NFS_IO_INPROGRESS);
DEFINE_WAIT_BIT(q, &c->flags, NFS_IO_INPROGRESS);
int ret = 0;
do {
prepare_to_wait(wq, &q.wait, TASK_KILLABLE);
set_bit(NFS_IO_INPROGRESS, &c->flags);
if (atomic_read(&c->io_count) == 0)
break;
ret = nfs_wait_bit_killable(&q.key, TASK_KILLABLE);
} while (atomic_read(&c->io_count) != 0 && !ret);
finish_wait(wq, &q.wait);
return ret;
}
/**
* nfs_iocounter_wait - wait for i/o to complete
* @c: nfs_io_counter to use
* @l_ctx: nfs_lock_context with io_counter to use
*
* returns -ERESTARTSYS if interrupted by a fatal signal.
* Otherwise returns 0 once the io_count hits 0.
*/
int
nfs_iocounter_wait(struct nfs_io_counter *c)
nfs_iocounter_wait(struct nfs_lock_context *l_ctx)
{
if (atomic_read(&c->io_count) == 0)
return 0;
return __nfs_iocounter_wait(c);
return wait_on_atomic_t(&l_ctx->io_count, nfs_wait_atomic_killable,
TASK_KILLABLE);
}
/*
@@ -370,7 +335,7 @@ nfs_create_request(struct nfs_open_context *ctx, struct page *page,
return ERR_CAST(l_ctx);
}
req->wb_lock_context = l_ctx;
nfs_iocounter_inc(&l_ctx->io_count);
atomic_inc(&l_ctx->io_count);
/* Initialize the request struct. Initially, we assume a
* long write-back delay. This will be adjusted in
@@ -431,7 +396,8 @@ static void nfs_clear_request(struct nfs_page *req)
req->wb_page = NULL;
}
if (l_ctx != NULL) {
nfs_iocounter_dec(&l_ctx->io_count);
if (atomic_dec_and_test(&l_ctx->io_count))
wake_up_atomic_t(&l_ctx->io_count);
nfs_put_lock_context(l_ctx);
req->wb_lock_context = NULL;
}