/**
* nfs_pageio_cond_complete - Conditional I/O completion
* @desc: pointer to io descriptor
* @index: page index
*
* It is important to ensure that processes don't try to take locks
* on non-contiguous ranges of pages as that might deadlock. This
* function should be called before attempting to wait on a locked
* nfs_page. It will complete the I/O if the page index 'index'
* is not contiguous with the existing list of pages in 'desc'.
*/
void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
{
if (!list_empty(&desc->pg_list)) {
struct nfs_page *prev = nfs_list_entry(desc->pg_list.prev);
if (index != prev->wb_index + 1)
nfs_pageio_doio(desc);
}
}
/**
* nfs_pageio_complete - Complete I/O on an nfs_pageio_descriptor
* @desc: pointer to io descriptor
*/
void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
{
for (;;) {
nfs_pageio_doio(desc);
if (!desc->pg_recoalesce)
break;
if (!nfs_do_recoalesce(desc))
break;
}
}
/**
* nfs_pageio_add_request - Attempt to coalesce a request into a page list.
* @desc: destination io descriptor
* @req: request
*
* Returns true if the request 'req' was successfully coalesced into the
* existing list of pages 'desc'.
*/
int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
struct nfs_page *req)
{
while (!nfs_pageio_do_add_request(desc, req)) {
nfs_pageio_doio(desc);
if (desc->pg_error < 0)
return 0;
}
return 1;
}
/**
* nfs_pageio_add_request - Attempt to coalesce a request into a page list.
* @desc: destination io descriptor
* @req: request
*
* Returns true if the request 'req' was successfully coalesced into the
* existing list of pages 'desc'.
*/
static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
struct nfs_page *req)
{
while (!nfs_pageio_do_add_request(desc, req)) {
desc->pg_moreio = 1;
nfs_pageio_doio(desc);
if (desc->pg_error < 0)
return 0;
desc->pg_moreio = 0;
if (desc->pg_recoalesce)
return 0;
}
return 1;
}
/**
* nfs_pageio_complete - Complete I/O on an nfs_pageio_descriptor
* @desc: pointer to io descriptor
*/
void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
{
nfs_pageio_doio(desc);
}
/**
* nfs_pageio_add_request - Attempt to coalesce a request into a page list.
* @desc: destination io descriptor
* @req: request
*
* This may split a request into subrequests which are all part of the
* same page group.
*
* Returns true if the request 'req' was successfully coalesced into the
* existing list of pages 'desc'.
*/
static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
struct nfs_page *req)
{
struct nfs_page *subreq;
unsigned int bytes_left = 0;
unsigned int offset, pgbase;
nfs_page_group_lock(req, false);
subreq = req;
bytes_left = subreq->wb_bytes;
offset = subreq->wb_offset;
pgbase = subreq->wb_pgbase;
do {
if (!nfs_pageio_do_add_request(desc, subreq)) {
/* make sure pg_test call(s) did nothing */
WARN_ON_ONCE(subreq->wb_bytes != bytes_left);
WARN_ON_ONCE(subreq->wb_offset != offset);
WARN_ON_ONCE(subreq->wb_pgbase != pgbase);
nfs_page_group_unlock(req);
desc->pg_moreio = 1;
nfs_pageio_doio(desc);
if (desc->pg_error < 0)
return 0;
if (desc->pg_recoalesce)
return 0;
/* retry add_request for this subreq */
nfs_page_group_lock(req, false);
continue;
}
/* check for buggy pg_test call(s) */
WARN_ON_ONCE(subreq->wb_bytes + subreq->wb_pgbase > PAGE_SIZE);
WARN_ON_ONCE(subreq->wb_bytes > bytes_left);
WARN_ON_ONCE(subreq->wb_bytes == 0);
bytes_left -= subreq->wb_bytes;
offset += subreq->wb_bytes;
pgbase += subreq->wb_bytes;
if (bytes_left) {
subreq = nfs_create_request(req->wb_context,
req->wb_page,
subreq, pgbase, bytes_left);
if (IS_ERR(subreq))
goto err_ptr;
nfs_lock_request(subreq);
subreq->wb_offset = offset;
subreq->wb_index = req->wb_index;
}
} while (bytes_left > 0);
nfs_page_group_unlock(req);
return 1;
err_ptr:
desc->pg_error = PTR_ERR(subreq);
nfs_page_group_unlock(req);
return 0;
}
