#include <linux/slab.h>
#include <linux/file.h>
+#include <linux/sched.h>
#include <linux/sunrpc/clnt.h>
#include <linux/nfs3.h>
#include <linux/nfs4.h>
#include <linux/nfs_page.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
-#include <linux/writeback.h>
-#define NFS_PARANOIA 1
+#include "internal.h"
static struct kmem_cache *nfs_page_cachep;
* @count: number of bytes to read/write
*
* The page must be locked by the caller. This makes sure we never
- * create two different requests for the same page, and avoids
- * a possible deadlock when we reach the hard limit on the number
- * of dirty pages.
+ * create two different requests for the same page.
* User should ensure it is safe to sleep in this function.
*/
struct nfs_page *
struct nfs_server *server = NFS_SERVER(inode);
struct nfs_page *req;
- /* Deal with hard limits. */
for (;;) {
/* try to allocate the request struct */
req = nfs_page_alloc();
if (req != NULL)
break;
- /* Try to free up at least one request in order to stay
- * below the hard limit
- */
if (signalled() && (server->flags & NFS_MOUNT_INTR))
return ERR_PTR(-ERESTARTSYS);
yield();
if (!atomic_dec_and_test(&req->wb_count))
return;
-#ifdef NFS_PARANOIA
- BUG_ON (!list_empty(&req->wb_list));
- BUG_ON (NFS_WBACK_BUSY(req));
-#endif
-
/* Release struct file or cached credential */
nfs_clear_request(req);
put_nfs_open_context(req->wb_context);
}
/**
- * nfs_coalesce_requests - Split coalesced requests out from a list.
- * @head: source list
- * @dst: destination list
- * @nmax: maximum number of requests to coalesce
+ * nfs_pageio_init - initialise a page io descriptor
+ * @desc: pointer to descriptor
+ * @inode: pointer to inode
+ * @doio: pointer to io function
+ * @bsize: io block size
+ * @io_flags: extra parameters for the io function
+ */
+void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
+ struct inode *inode,
+ int (*doio)(struct inode *, struct list_head *, unsigned int, size_t, int),
+ size_t bsize,
+ int io_flags)
+{
+ INIT_LIST_HEAD(&desc->pg_list);
+ desc->pg_bytes_written = 0;
+ desc->pg_count = 0;
+ desc->pg_bsize = bsize;
+ desc->pg_base = 0;
+ desc->pg_inode = inode;
+ desc->pg_doio = doio;
+ desc->pg_ioflags = io_flags;
+ desc->pg_error = 0;
+}
+
+/**
+ * nfs_can_coalesce_requests - test two requests for compatibility
+ * @prev: pointer to nfs_page
+ * @req: pointer to nfs_page
*
- * Moves a maximum of 'nmax' elements from one list to another.
- * The elements are checked to ensure that they form a contiguous set
- * of pages, and that the RPC credentials are the same.
+ * The nfs_page structures 'prev' and 'req' are compared to ensure that the
+ * page data area they describe is contiguous, and that their RPC
+ * credentials, NFSv4 open state, and lockowners are the same.
+ *
+ * Return 'true' if this is the case, else return 'false'.
*/
-int
-nfs_coalesce_requests(struct list_head *head, struct list_head *dst,
- unsigned int nmax)
+static int nfs_can_coalesce_requests(struct nfs_page *prev,
+ struct nfs_page *req)
{
- struct nfs_page *req = NULL;
- unsigned int npages = 0;
-
- while (!list_empty(head)) {
- struct nfs_page *prev = req;
-
- req = nfs_list_entry(head->next);
- if (prev) {
- if (req->wb_context->cred != prev->wb_context->cred)
- break;
- if (req->wb_context->lockowner != prev->wb_context->lockowner)
- break;
- if (req->wb_context->state != prev->wb_context->state)
- break;
- if (req->wb_index != (prev->wb_index + 1))
- break;
-
- if (req->wb_pgbase != 0)
- break;
- }
- nfs_list_remove_request(req);
- nfs_list_add_request(req, dst);
- npages++;
- if (req->wb_pgbase + req->wb_bytes != PAGE_CACHE_SIZE)
- break;
- if (npages >= nmax)
- break;
- }
- return npages;
+ if (req->wb_context->cred != prev->wb_context->cred)
+ return 0;
+ if (req->wb_context->lockowner != prev->wb_context->lockowner)
+ return 0;
+ if (req->wb_context->state != prev->wb_context->state)
+ return 0;
+ if (req->wb_index != (prev->wb_index + 1))
+ return 0;
+ if (req->wb_pgbase != 0)
+ return 0;
+ if (prev->wb_pgbase + prev->wb_bytes != PAGE_CACHE_SIZE)
+ return 0;
+ return 1;
}
-#define NFS_SCAN_MAXENTRIES 16
/**
- * nfs_scan_dirty - Scan the radix tree for dirty requests
- * @mapping: pointer to address space
- * @wbc: writeback_control structure
- * @dst: Destination list
+ * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
+ * @desc: destination io descriptor
+ * @req: request
*
- * 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
+ * Returns true if the request 'req' was successfully coalesced into the
+ * existing list of pages 'desc'.
*/
-long nfs_scan_dirty(struct address_space *mapping,
- struct writeback_control *wbc,
- struct list_head *dst)
+static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
+ struct nfs_page *req)
{
- struct nfs_inode *nfsi = NFS_I(mapping->host);
- struct nfs_page *pgvec[NFS_SCAN_MAXENTRIES];
- struct nfs_page *req;
- pgoff_t idx_start, idx_end;
- long res = 0;
- int found, i;
+ size_t newlen = req->wb_bytes;
- if (nfsi->ndirty == 0)
- return 0;
- if (wbc->range_cyclic) {
- idx_start = 0;
- idx_end = ULONG_MAX;
- } else if (wbc->range_end == 0) {
- idx_start = wbc->range_start >> PAGE_CACHE_SHIFT;
- idx_end = ULONG_MAX;
- } else {
- idx_start = wbc->range_start >> PAGE_CACHE_SHIFT;
- idx_end = wbc->range_end >> PAGE_CACHE_SHIFT;
- }
+ if (desc->pg_count != 0) {
+ struct nfs_page *prev;
- for (;;) {
- unsigned int toscan = NFS_SCAN_MAXENTRIES;
+ /*
+ * FIXME: ideally we should be able to coalesce all requests
+ * that are not block boundary aligned, but currently this
+ * is problematic for the case of bsize < PAGE_CACHE_SIZE,
+ * since nfs_flush_multi and nfs_pagein_multi assume you
+ * can have only one struct nfs_page.
+ */
+ if (desc->pg_bsize < PAGE_SIZE)
+ return 0;
+ newlen += desc->pg_count;
+ if (newlen > desc->pg_bsize)
+ return 0;
+ prev = nfs_list_entry(desc->pg_list.prev);
+ if (!nfs_can_coalesce_requests(prev, req))
+ return 0;
+ } else
+ desc->pg_base = req->wb_pgbase;
+ nfs_list_remove_request(req);
+ nfs_list_add_request(req, &desc->pg_list);
+ desc->pg_count = newlen;
+ return 1;
+}
- found = radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree,
- (void **)&pgvec[0], idx_start, toscan,
- NFS_PAGE_TAG_DIRTY);
+/*
+ * Helper for nfs_pageio_add_request and nfs_pageio_complete
+ */
+static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
+{
+ if (!list_empty(&desc->pg_list)) {
+ int error = desc->pg_doio(desc->pg_inode,
+ &desc->pg_list,
+ nfs_page_array_len(desc->pg_base,
+ desc->pg_count),
+ desc->pg_count,
+ desc->pg_ioflags);
+ if (error < 0)
+ desc->pg_error = error;
+ else
+ desc->pg_bytes_written += desc->pg_count;
+ }
+ if (list_empty(&desc->pg_list)) {
+ desc->pg_count = 0;
+ desc->pg_base = 0;
+ }
+}
- /* Did we make progress? */
- if (found <= 0)
- 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;
+}
- for (i = 0; i < found; i++) {
- req = pgvec[i];
- if (!wbc->range_cyclic && req->wb_index > idx_end)
- goto out;
+/**
+ * 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);
+}
- /* Try to lock request and mark it for writeback */
- if (!nfs_set_page_writeback_locked(req))
- goto next;
- radix_tree_tag_clear(&nfsi->nfs_page_tree,
- req->wb_index, NFS_PAGE_TAG_DIRTY);
- nfsi->ndirty--;
- nfs_list_remove_request(req);
- nfs_list_add_request(req, dst);
- res++;
- if (res == LONG_MAX)
- goto out;
-next:
- idx_start = req->wb_index + 1;
- }
+/**
+ * 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);
}
-out:
- WARN_ON ((nfsi->ndirty == 0) != list_empty(&nfsi->dirty));
- return res;
}
+#define NFS_SCAN_MAXENTRIES 16
/**
* nfs_scan_list - Scan a list for matching requests
* @nfsi: NFS inode
* You must be holding the inode's req_lock when calling this function
*/
int nfs_scan_list(struct nfs_inode *nfsi, struct list_head *head,
- struct list_head *dst, unsigned long idx_start,
+ struct list_head *dst, pgoff_t idx_start,
unsigned int npages)
{
struct nfs_page *pgvec[NFS_SCAN_MAXENTRIES];
struct nfs_page *req;
- unsigned long idx_end;
+ pgoff_t idx_end;
int found, i;
int res;
git.openpandora.org / pandora-kernel.git / blobdiff