/**
* nfs_scan_list - Scan a list for matching requests
* @head: One of the NFS inode request lists
* @dst: Destination list
* @idx_start: lower bound of page->index to scan
* @npages: idx_start + npages sets the upper bound to scan.
*
* Moves elements from one of the inode request lists.
* If the number of requests is set to 0, the entire address_space
* starting at index idx_start, is scanned.
* The requests are *not* checked to ensure that they form a contiguous set.
* You must be holding the inode's req_lock when calling this function
*/
int
nfs_scan_list(struct list_head *head, struct list_head *dst,
unsigned long idx_start, unsigned int npages)
{
struct list_head *pos, *tmp;
struct nfs_page *req;
unsigned long idx_end;
int res;
res = 0;
if (npages == 0)
idx_end = ~0;
else
idx_end = idx_start + npages - 1;
list_for_each_safe(pos, tmp, head) {
req = nfs_list_entry(pos);
if (req->wb_index < idx_start)
continue;
if (req->wb_index > idx_end)
break;
if (!nfs_lock_request(req))
continue;
nfs_list_remove_request(req);
nfs_list_add_request(req, dst);
res++;
}
/**
* nfs_set_page_writeback_locked - Lock a request for writeback
* @req:
*/
int nfs_set_page_writeback_locked(struct nfs_page *req)
{
struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);
if (!nfs_lock_request(req))
return 0;
radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_WRITEBACK);
return 1;
}
/**
* nfs_set_page_tag_locked - Tag a request as locked
* @req:
*/
static int nfs_set_page_tag_locked(struct nfs_page *req)
{
struct nfs_inode *nfsi = NFS_I(req->wb_context->path.dentry->d_inode);
if (!nfs_lock_request(req))
return 0;
radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_LOCKED);
return 1;
}
/**
* 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;
}