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![Trond Myklebust](/assets/img/avatar_default.png)
When coalescing requests into a single READ or WRITE RPC call, and there is no file locking involved, we don't have to refuse coalescing for requests where the lock owner information doesn't match. Reported-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
537 lines
14 KiB
C
537 lines
14 KiB
C
/*
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* linux/fs/nfs/pagelist.c
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*
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* A set of helper functions for managing NFS read and write requests.
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* The main purpose of these routines is to provide support for the
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* coalescing of several requests into a single RPC call.
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*
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* Copyright 2000, 2001 (c) Trond Myklebust <trond.myklebust@fys.uio.no>
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*
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*/
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#include <linux/slab.h>
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#include <linux/file.h>
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#include <linux/sched.h>
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#include <linux/sunrpc/clnt.h>
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#include <linux/nfs.h>
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#include <linux/nfs3.h>
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#include <linux/nfs4.h>
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#include <linux/nfs_page.h>
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#include <linux/nfs_fs.h>
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#include <linux/nfs_mount.h>
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#include <linux/export.h>
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#include "internal.h"
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#include "pnfs.h"
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static struct kmem_cache *nfs_page_cachep;
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bool nfs_pgarray_set(struct nfs_page_array *p, unsigned int pagecount)
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{
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p->npages = pagecount;
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if (pagecount <= ARRAY_SIZE(p->page_array))
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p->pagevec = p->page_array;
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else {
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p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_KERNEL);
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if (!p->pagevec)
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p->npages = 0;
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}
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return p->pagevec != NULL;
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}
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void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
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struct nfs_pgio_header *hdr,
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void (*release)(struct nfs_pgio_header *hdr))
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{
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hdr->req = nfs_list_entry(desc->pg_list.next);
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hdr->inode = desc->pg_inode;
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hdr->cred = hdr->req->wb_context->cred;
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hdr->io_start = req_offset(hdr->req);
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hdr->good_bytes = desc->pg_count;
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hdr->dreq = desc->pg_dreq;
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hdr->layout_private = desc->pg_layout_private;
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hdr->release = release;
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hdr->completion_ops = desc->pg_completion_ops;
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if (hdr->completion_ops->init_hdr)
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hdr->completion_ops->init_hdr(hdr);
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}
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EXPORT_SYMBOL_GPL(nfs_pgheader_init);
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void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos)
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{
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spin_lock(&hdr->lock);
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if (pos < hdr->io_start + hdr->good_bytes) {
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set_bit(NFS_IOHDR_ERROR, &hdr->flags);
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clear_bit(NFS_IOHDR_EOF, &hdr->flags);
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hdr->good_bytes = pos - hdr->io_start;
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hdr->error = error;
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}
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spin_unlock(&hdr->lock);
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}
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static inline struct nfs_page *
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nfs_page_alloc(void)
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{
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struct nfs_page *p = kmem_cache_zalloc(nfs_page_cachep, GFP_NOIO);
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if (p)
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INIT_LIST_HEAD(&p->wb_list);
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return p;
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}
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static inline void
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nfs_page_free(struct nfs_page *p)
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{
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kmem_cache_free(nfs_page_cachep, p);
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}
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static void
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nfs_iocounter_inc(struct nfs_io_counter *c)
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{
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atomic_inc(&c->io_count);
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}
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static void
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nfs_iocounter_dec(struct nfs_io_counter *c)
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{
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if (atomic_dec_and_test(&c->io_count)) {
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clear_bit(NFS_IO_INPROGRESS, &c->flags);
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smp_mb__after_clear_bit();
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wake_up_bit(&c->flags, NFS_IO_INPROGRESS);
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}
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}
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static int
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__nfs_iocounter_wait(struct nfs_io_counter *c)
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{
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wait_queue_head_t *wq = bit_waitqueue(&c->flags, NFS_IO_INPROGRESS);
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DEFINE_WAIT_BIT(q, &c->flags, NFS_IO_INPROGRESS);
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int ret = 0;
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do {
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prepare_to_wait(wq, &q.wait, TASK_KILLABLE);
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set_bit(NFS_IO_INPROGRESS, &c->flags);
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if (atomic_read(&c->io_count) == 0)
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break;
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ret = nfs_wait_bit_killable(&c->flags);
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} while (atomic_read(&c->io_count) != 0);
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finish_wait(wq, &q.wait);
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return ret;
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}
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/**
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* nfs_iocounter_wait - wait for i/o to complete
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* @c: nfs_io_counter to use
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*
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* returns -ERESTARTSYS if interrupted by a fatal signal.
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* Otherwise returns 0 once the io_count hits 0.
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*/
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int
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nfs_iocounter_wait(struct nfs_io_counter *c)
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{
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if (atomic_read(&c->io_count) == 0)
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return 0;
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return __nfs_iocounter_wait(c);
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}
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/**
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* nfs_create_request - Create an NFS read/write request.
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* @ctx: open context to use
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* @inode: inode to which the request is attached
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* @page: page to write
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* @offset: starting offset within the page for the write
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* @count: number of bytes to read/write
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*
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* The page must be locked by the caller. This makes sure we never
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* create two different requests for the same page.
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* User should ensure it is safe to sleep in this function.
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*/
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struct nfs_page *
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nfs_create_request(struct nfs_open_context *ctx, struct inode *inode,
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struct page *page,
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unsigned int offset, unsigned int count)
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{
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struct nfs_page *req;
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struct nfs_lock_context *l_ctx;
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if (test_bit(NFS_CONTEXT_BAD, &ctx->flags))
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return ERR_PTR(-EBADF);
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/* try to allocate the request struct */
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req = nfs_page_alloc();
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if (req == NULL)
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return ERR_PTR(-ENOMEM);
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/* get lock context early so we can deal with alloc failures */
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l_ctx = nfs_get_lock_context(ctx);
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if (IS_ERR(l_ctx)) {
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nfs_page_free(req);
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return ERR_CAST(l_ctx);
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}
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req->wb_lock_context = l_ctx;
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nfs_iocounter_inc(&l_ctx->io_count);
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/* Initialize the request struct. Initially, we assume a
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* long write-back delay. This will be adjusted in
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* update_nfs_request below if the region is not locked. */
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req->wb_page = page;
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req->wb_index = page_file_index(page);
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page_cache_get(page);
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req->wb_offset = offset;
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req->wb_pgbase = offset;
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req->wb_bytes = count;
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req->wb_context = get_nfs_open_context(ctx);
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kref_init(&req->wb_kref);
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return req;
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}
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/**
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* nfs_unlock_request - Unlock request and wake up sleepers.
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* @req:
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*/
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void nfs_unlock_request(struct nfs_page *req)
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{
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if (!NFS_WBACK_BUSY(req)) {
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printk(KERN_ERR "NFS: Invalid unlock attempted\n");
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BUG();
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}
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smp_mb__before_clear_bit();
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clear_bit(PG_BUSY, &req->wb_flags);
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smp_mb__after_clear_bit();
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wake_up_bit(&req->wb_flags, PG_BUSY);
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}
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/**
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* nfs_unlock_and_release_request - Unlock request and release the nfs_page
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* @req:
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*/
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void nfs_unlock_and_release_request(struct nfs_page *req)
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{
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nfs_unlock_request(req);
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nfs_release_request(req);
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}
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/*
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* nfs_clear_request - Free up all resources allocated to the request
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* @req:
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*
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* Release page and open context resources associated with a read/write
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* request after it has completed.
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*/
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static void nfs_clear_request(struct nfs_page *req)
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{
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struct page *page = req->wb_page;
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struct nfs_open_context *ctx = req->wb_context;
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struct nfs_lock_context *l_ctx = req->wb_lock_context;
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if (page != NULL) {
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page_cache_release(page);
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req->wb_page = NULL;
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}
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if (l_ctx != NULL) {
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nfs_iocounter_dec(&l_ctx->io_count);
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nfs_put_lock_context(l_ctx);
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req->wb_lock_context = NULL;
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}
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if (ctx != NULL) {
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put_nfs_open_context(ctx);
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req->wb_context = NULL;
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}
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}
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/**
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* nfs_release_request - Release the count on an NFS read/write request
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* @req: request to release
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*
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* Note: Should never be called with the spinlock held!
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*/
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static void nfs_free_request(struct kref *kref)
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{
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struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
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/* Release struct file and open context */
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nfs_clear_request(req);
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nfs_page_free(req);
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}
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void nfs_release_request(struct nfs_page *req)
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{
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kref_put(&req->wb_kref, nfs_free_request);
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}
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static int nfs_wait_bit_uninterruptible(void *word)
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{
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io_schedule();
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return 0;
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}
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/**
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* nfs_wait_on_request - Wait for a request to complete.
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* @req: request to wait upon.
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*
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* Interruptible by fatal signals only.
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* The user is responsible for holding a count on the request.
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*/
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int
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nfs_wait_on_request(struct nfs_page *req)
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{
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return wait_on_bit(&req->wb_flags, PG_BUSY,
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nfs_wait_bit_uninterruptible,
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TASK_UNINTERRUPTIBLE);
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}
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bool nfs_generic_pg_test(struct nfs_pageio_descriptor *desc, struct nfs_page *prev, struct nfs_page *req)
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{
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/*
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* FIXME: ideally we should be able to coalesce all requests
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* that are not block boundary aligned, but currently this
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* is problematic for the case of bsize < PAGE_CACHE_SIZE,
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* since nfs_flush_multi and nfs_pagein_multi assume you
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* can have only one struct nfs_page.
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*/
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if (desc->pg_bsize < PAGE_SIZE)
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return 0;
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return desc->pg_count + req->wb_bytes <= desc->pg_bsize;
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}
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EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
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/**
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* nfs_pageio_init - initialise a page io descriptor
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* @desc: pointer to descriptor
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* @inode: pointer to inode
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* @doio: pointer to io function
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* @bsize: io block size
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* @io_flags: extra parameters for the io function
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*/
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void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
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struct inode *inode,
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const struct nfs_pageio_ops *pg_ops,
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const struct nfs_pgio_completion_ops *compl_ops,
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size_t bsize,
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int io_flags)
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{
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INIT_LIST_HEAD(&desc->pg_list);
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desc->pg_bytes_written = 0;
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desc->pg_count = 0;
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desc->pg_bsize = bsize;
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desc->pg_base = 0;
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desc->pg_moreio = 0;
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desc->pg_recoalesce = 0;
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desc->pg_inode = inode;
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desc->pg_ops = pg_ops;
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desc->pg_completion_ops = compl_ops;
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desc->pg_ioflags = io_flags;
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desc->pg_error = 0;
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desc->pg_lseg = NULL;
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desc->pg_dreq = NULL;
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desc->pg_layout_private = NULL;
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}
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EXPORT_SYMBOL_GPL(nfs_pageio_init);
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static bool nfs_match_open_context(const struct nfs_open_context *ctx1,
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const struct nfs_open_context *ctx2)
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{
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return ctx1->cred == ctx2->cred && ctx1->state == ctx2->state;
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}
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static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
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const struct nfs_lock_context *l2)
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{
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return l1->lockowner.l_owner == l2->lockowner.l_owner
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&& l1->lockowner.l_pid == l2->lockowner.l_pid;
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}
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/**
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* nfs_can_coalesce_requests - test two requests for compatibility
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* @prev: pointer to nfs_page
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* @req: pointer to nfs_page
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*
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* The nfs_page structures 'prev' and 'req' are compared to ensure that the
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* page data area they describe is contiguous, and that their RPC
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* credentials, NFSv4 open state, and lockowners are the same.
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*
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* Return 'true' if this is the case, else return 'false'.
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*/
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static bool nfs_can_coalesce_requests(struct nfs_page *prev,
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struct nfs_page *req,
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struct nfs_pageio_descriptor *pgio)
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{
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if (!nfs_match_open_context(req->wb_context, prev->wb_context))
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return false;
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if (req->wb_context->dentry->d_inode->i_flock != NULL &&
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!nfs_match_lock_context(req->wb_lock_context, prev->wb_lock_context))
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return false;
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if (req->wb_pgbase != 0)
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return false;
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if (prev->wb_pgbase + prev->wb_bytes != PAGE_CACHE_SIZE)
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return false;
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if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
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return false;
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return pgio->pg_ops->pg_test(pgio, prev, req);
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}
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/**
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* nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
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* @desc: destination io descriptor
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* @req: request
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*
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* Returns true if the request 'req' was successfully coalesced into the
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* existing list of pages 'desc'.
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*/
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static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
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struct nfs_page *req)
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{
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if (desc->pg_count != 0) {
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struct nfs_page *prev;
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prev = nfs_list_entry(desc->pg_list.prev);
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if (!nfs_can_coalesce_requests(prev, req, desc))
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return 0;
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} else {
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if (desc->pg_ops->pg_init)
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desc->pg_ops->pg_init(desc, req);
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desc->pg_base = req->wb_pgbase;
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}
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nfs_list_remove_request(req);
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nfs_list_add_request(req, &desc->pg_list);
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desc->pg_count += req->wb_bytes;
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return 1;
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}
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/*
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* Helper for nfs_pageio_add_request and nfs_pageio_complete
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*/
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static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
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{
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if (!list_empty(&desc->pg_list)) {
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int error = desc->pg_ops->pg_doio(desc);
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if (error < 0)
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desc->pg_error = error;
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else
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desc->pg_bytes_written += desc->pg_count;
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}
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if (list_empty(&desc->pg_list)) {
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desc->pg_count = 0;
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desc->pg_base = 0;
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}
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}
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/**
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* nfs_pageio_add_request - Attempt to coalesce a request into a page list.
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* @desc: destination io descriptor
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* @req: request
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*
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* Returns true if the request 'req' was successfully coalesced into the
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* existing list of pages 'desc'.
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*/
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static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
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struct nfs_page *req)
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{
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while (!nfs_pageio_do_add_request(desc, req)) {
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desc->pg_moreio = 1;
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nfs_pageio_doio(desc);
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if (desc->pg_error < 0)
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return 0;
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desc->pg_moreio = 0;
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if (desc->pg_recoalesce)
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return 0;
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}
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return 1;
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}
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static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
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{
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LIST_HEAD(head);
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do {
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list_splice_init(&desc->pg_list, &head);
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desc->pg_bytes_written -= desc->pg_count;
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desc->pg_count = 0;
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desc->pg_base = 0;
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desc->pg_recoalesce = 0;
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while (!list_empty(&head)) {
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struct nfs_page *req;
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req = list_first_entry(&head, struct nfs_page, wb_list);
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nfs_list_remove_request(req);
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if (__nfs_pageio_add_request(desc, req))
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continue;
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if (desc->pg_error < 0)
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return 0;
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break;
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}
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} while (desc->pg_recoalesce);
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return 1;
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}
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int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
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struct nfs_page *req)
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{
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int ret;
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do {
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ret = __nfs_pageio_add_request(desc, req);
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if (ret)
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break;
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if (desc->pg_error < 0)
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break;
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ret = nfs_do_recoalesce(desc);
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} while (ret);
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return ret;
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}
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EXPORT_SYMBOL_GPL(nfs_pageio_add_request);
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/**
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* nfs_pageio_complete - Complete I/O on an nfs_pageio_descriptor
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* @desc: pointer to io descriptor
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*/
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void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
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{
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for (;;) {
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nfs_pageio_doio(desc);
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if (!desc->pg_recoalesce)
|
|
break;
|
|
if (!nfs_do_recoalesce(desc))
|
|
break;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(nfs_pageio_complete);
|
|
|
|
/**
|
|
* 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_complete(desc);
|
|
}
|
|
}
|
|
|
|
int __init nfs_init_nfspagecache(void)
|
|
{
|
|
nfs_page_cachep = kmem_cache_create("nfs_page",
|
|
sizeof(struct nfs_page),
|
|
0, SLAB_HWCACHE_ALIGN,
|
|
NULL);
|
|
if (nfs_page_cachep == NULL)
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
void nfs_destroy_nfspagecache(void)
|
|
{
|
|
kmem_cache_destroy(nfs_page_cachep);
|
|
}
|
|
|