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464 lines
12 KiB
464 lines
12 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* linux/fs/nfs/read.c |
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* |
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* Block I/O for NFS |
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* |
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* Partial copy of Linus' read cache modifications to fs/nfs/file.c |
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* modified for async RPC by [email protected] |
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*/ |
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#include <linux/time.h> |
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#include <linux/kernel.h> |
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#include <linux/errno.h> |
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#include <linux/fcntl.h> |
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#include <linux/stat.h> |
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#include <linux/mm.h> |
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#include <linux/slab.h> |
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#include <linux/pagemap.h> |
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#include <linux/sunrpc/clnt.h> |
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#include <linux/nfs_fs.h> |
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#include <linux/nfs_page.h> |
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#include <linux/module.h> |
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#include "nfs4_fs.h" |
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#include "internal.h" |
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#include "iostat.h" |
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#include "fscache.h" |
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#include "pnfs.h" |
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#include "nfstrace.h" |
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#define NFSDBG_FACILITY NFSDBG_PAGECACHE |
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static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops; |
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static const struct nfs_rw_ops nfs_rw_read_ops; |
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static struct kmem_cache *nfs_rdata_cachep; |
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static struct nfs_pgio_header *nfs_readhdr_alloc(void) |
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{ |
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struct nfs_pgio_header *p = kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL); |
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if (p) |
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p->rw_mode = FMODE_READ; |
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return p; |
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} |
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static void nfs_readhdr_free(struct nfs_pgio_header *rhdr) |
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{ |
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kmem_cache_free(nfs_rdata_cachep, rhdr); |
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} |
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static |
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int nfs_return_empty_page(struct page *page) |
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{ |
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zero_user(page, 0, PAGE_SIZE); |
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SetPageUptodate(page); |
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unlock_page(page); |
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return 0; |
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} |
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void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio, |
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struct inode *inode, bool force_mds, |
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const struct nfs_pgio_completion_ops *compl_ops) |
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{ |
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struct nfs_server *server = NFS_SERVER(inode); |
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const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops; |
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#ifdef CONFIG_NFS_V4_1 |
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if (server->pnfs_curr_ld && !force_mds) |
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pg_ops = server->pnfs_curr_ld->pg_read_ops; |
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#endif |
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nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_read_ops, |
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server->rsize, 0); |
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} |
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EXPORT_SYMBOL_GPL(nfs_pageio_init_read); |
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static void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio) |
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{ |
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struct nfs_pgio_mirror *pgm; |
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unsigned long npages; |
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nfs_pageio_complete(pgio); |
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/* It doesn't make sense to do mirrored reads! */ |
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WARN_ON_ONCE(pgio->pg_mirror_count != 1); |
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pgm = &pgio->pg_mirrors[0]; |
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NFS_I(pgio->pg_inode)->read_io += pgm->pg_bytes_written; |
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npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >> PAGE_SHIFT; |
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nfs_add_stats(pgio->pg_inode, NFSIOS_READPAGES, npages); |
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} |
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void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio) |
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{ |
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struct nfs_pgio_mirror *mirror; |
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if (pgio->pg_ops && pgio->pg_ops->pg_cleanup) |
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pgio->pg_ops->pg_cleanup(pgio); |
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pgio->pg_ops = &nfs_pgio_rw_ops; |
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/* read path should never have more than one mirror */ |
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WARN_ON_ONCE(pgio->pg_mirror_count != 1); |
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mirror = &pgio->pg_mirrors[0]; |
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mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize; |
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} |
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EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds); |
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static void nfs_readpage_release(struct nfs_page *req, int error) |
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{ |
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struct inode *inode = d_inode(nfs_req_openctx(req)->dentry); |
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struct page *page = req->wb_page; |
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dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id, |
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(unsigned long long)NFS_FILEID(inode), req->wb_bytes, |
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(long long)req_offset(req)); |
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if (nfs_error_is_fatal_on_server(error) && error != -ETIMEDOUT) |
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SetPageError(page); |
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if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) { |
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struct address_space *mapping = page_file_mapping(page); |
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if (PageUptodate(page)) |
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nfs_readpage_to_fscache(inode, page, 0); |
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else if (!PageError(page) && !PagePrivate(page)) |
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generic_error_remove_page(mapping, page); |
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unlock_page(page); |
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} |
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nfs_release_request(req); |
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} |
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struct nfs_readdesc { |
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struct nfs_pageio_descriptor pgio; |
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struct nfs_open_context *ctx; |
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}; |
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static void nfs_page_group_set_uptodate(struct nfs_page *req) |
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{ |
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if (nfs_page_group_sync_on_bit(req, PG_UPTODATE)) |
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SetPageUptodate(req->wb_page); |
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} |
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static void nfs_read_completion(struct nfs_pgio_header *hdr) |
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{ |
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unsigned long bytes = 0; |
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int error; |
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if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) |
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goto out; |
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while (!list_empty(&hdr->pages)) { |
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struct nfs_page *req = nfs_list_entry(hdr->pages.next); |
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struct page *page = req->wb_page; |
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unsigned long start = req->wb_pgbase; |
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unsigned long end = req->wb_pgbase + req->wb_bytes; |
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if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) { |
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/* note: regions of the page not covered by a |
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* request are zeroed in readpage_async_filler */ |
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if (bytes > hdr->good_bytes) { |
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/* nothing in this request was good, so zero |
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* the full extent of the request */ |
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zero_user_segment(page, start, end); |
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} else if (hdr->good_bytes - bytes < req->wb_bytes) { |
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/* part of this request has good bytes, but |
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* not all. zero the bad bytes */ |
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start += hdr->good_bytes - bytes; |
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WARN_ON(start < req->wb_pgbase); |
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zero_user_segment(page, start, end); |
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} |
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} |
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error = 0; |
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bytes += req->wb_bytes; |
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if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) { |
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if (bytes <= hdr->good_bytes) |
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nfs_page_group_set_uptodate(req); |
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else { |
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error = hdr->error; |
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xchg(&nfs_req_openctx(req)->error, error); |
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} |
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} else |
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nfs_page_group_set_uptodate(req); |
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nfs_list_remove_request(req); |
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nfs_readpage_release(req, error); |
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} |
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out: |
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hdr->release(hdr); |
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} |
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static void nfs_initiate_read(struct nfs_pgio_header *hdr, |
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struct rpc_message *msg, |
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const struct nfs_rpc_ops *rpc_ops, |
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struct rpc_task_setup *task_setup_data, int how) |
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{ |
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struct inode *inode = hdr->inode; |
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int swap_flags = IS_SWAPFILE(inode) ? NFS_RPC_SWAPFLAGS : 0; |
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task_setup_data->flags |= swap_flags; |
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rpc_ops->read_setup(hdr, msg); |
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trace_nfs_initiate_read(hdr); |
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} |
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static void |
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nfs_async_read_error(struct list_head *head, int error) |
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{ |
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struct nfs_page *req; |
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while (!list_empty(head)) { |
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req = nfs_list_entry(head->next); |
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nfs_list_remove_request(req); |
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nfs_readpage_release(req, error); |
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} |
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} |
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static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = { |
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.error_cleanup = nfs_async_read_error, |
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.completion = nfs_read_completion, |
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}; |
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/* |
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* This is the callback from RPC telling us whether a reply was |
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* received or some error occurred (timeout or socket shutdown). |
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*/ |
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static int nfs_readpage_done(struct rpc_task *task, |
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struct nfs_pgio_header *hdr, |
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struct inode *inode) |
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{ |
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int status = NFS_PROTO(inode)->read_done(task, hdr); |
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if (status != 0) |
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return status; |
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nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count); |
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trace_nfs_readpage_done(task, hdr); |
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if (task->tk_status == -ESTALE) { |
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nfs_set_inode_stale(inode); |
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nfs_mark_for_revalidate(inode); |
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} |
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return 0; |
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} |
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static void nfs_readpage_retry(struct rpc_task *task, |
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struct nfs_pgio_header *hdr) |
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{ |
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struct nfs_pgio_args *argp = &hdr->args; |
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struct nfs_pgio_res *resp = &hdr->res; |
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/* This is a short read! */ |
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nfs_inc_stats(hdr->inode, NFSIOS_SHORTREAD); |
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trace_nfs_readpage_short(task, hdr); |
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/* Has the server at least made some progress? */ |
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if (resp->count == 0) { |
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nfs_set_pgio_error(hdr, -EIO, argp->offset); |
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return; |
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} |
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/* For non rpc-based layout drivers, retry-through-MDS */ |
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if (!task->tk_ops) { |
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hdr->pnfs_error = -EAGAIN; |
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return; |
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} |
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/* Yes, so retry the read at the end of the hdr */ |
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hdr->mds_offset += resp->count; |
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argp->offset += resp->count; |
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argp->pgbase += resp->count; |
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argp->count -= resp->count; |
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resp->count = 0; |
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resp->eof = 0; |
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rpc_restart_call_prepare(task); |
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} |
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static void nfs_readpage_result(struct rpc_task *task, |
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struct nfs_pgio_header *hdr) |
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{ |
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if (hdr->res.eof) { |
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loff_t pos = hdr->args.offset + hdr->res.count; |
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unsigned int new = pos - hdr->io_start; |
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if (hdr->good_bytes > new) { |
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hdr->good_bytes = new; |
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set_bit(NFS_IOHDR_EOF, &hdr->flags); |
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clear_bit(NFS_IOHDR_ERROR, &hdr->flags); |
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} |
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} else if (hdr->res.count < hdr->args.count) |
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nfs_readpage_retry(task, hdr); |
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} |
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static int |
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readpage_async_filler(void *data, struct page *page) |
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{ |
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struct nfs_readdesc *desc = data; |
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struct nfs_page *new; |
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unsigned int len; |
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int error; |
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len = nfs_page_length(page); |
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if (len == 0) |
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return nfs_return_empty_page(page); |
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new = nfs_create_request(desc->ctx, page, 0, len); |
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if (IS_ERR(new)) |
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goto out_error; |
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if (len < PAGE_SIZE) |
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zero_user_segment(page, len, PAGE_SIZE); |
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if (!nfs_pageio_add_request(&desc->pgio, new)) { |
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nfs_list_remove_request(new); |
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error = desc->pgio.pg_error; |
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nfs_readpage_release(new, error); |
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goto out; |
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} |
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return 0; |
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out_error: |
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error = PTR_ERR(new); |
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unlock_page(page); |
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out: |
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return error; |
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} |
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/* |
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* Read a page over NFS. |
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* We read the page synchronously in the following case: |
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* - The error flag is set for this page. This happens only when a |
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* previous async read operation failed. |
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*/ |
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int nfs_readpage(struct file *file, struct page *page) |
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{ |
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struct nfs_readdesc desc; |
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struct inode *inode = page_file_mapping(page)->host; |
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int ret; |
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dprintk("NFS: nfs_readpage (%p %ld@%lu)\n", |
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page, PAGE_SIZE, page_index(page)); |
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nfs_inc_stats(inode, NFSIOS_VFSREADPAGE); |
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/* |
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* Try to flush any pending writes to the file.. |
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* |
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* NOTE! Because we own the page lock, there cannot |
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* be any new pending writes generated at this point |
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* for this page (other pages can be written to). |
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*/ |
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ret = nfs_wb_page(inode, page); |
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if (ret) |
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goto out_unlock; |
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if (PageUptodate(page)) |
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goto out_unlock; |
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ret = -ESTALE; |
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if (NFS_STALE(inode)) |
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goto out_unlock; |
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if (file == NULL) { |
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ret = -EBADF; |
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desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ); |
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if (desc.ctx == NULL) |
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goto out_unlock; |
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} else |
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desc.ctx = get_nfs_open_context(nfs_file_open_context(file)); |
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xchg(&desc.ctx->error, 0); |
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if (!IS_SYNC(inode)) { |
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ret = nfs_readpage_from_fscache(desc.ctx, inode, page); |
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if (ret == 0) |
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goto out_wait; |
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} |
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nfs_pageio_init_read(&desc.pgio, inode, false, |
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&nfs_async_read_completion_ops); |
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ret = readpage_async_filler(&desc, page); |
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if (ret) |
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goto out; |
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nfs_pageio_complete_read(&desc.pgio); |
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ret = desc.pgio.pg_error < 0 ? desc.pgio.pg_error : 0; |
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out_wait: |
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if (!ret) { |
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ret = wait_on_page_locked_killable(page); |
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if (!PageUptodate(page) && !ret) |
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ret = xchg(&desc.ctx->error, 0); |
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} |
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out: |
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put_nfs_open_context(desc.ctx); |
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return ret; |
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out_unlock: |
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unlock_page(page); |
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return ret; |
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} |
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int nfs_readpages(struct file *file, struct address_space *mapping, |
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struct list_head *pages, unsigned nr_pages) |
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{ |
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struct nfs_readdesc desc; |
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struct inode *inode = mapping->host; |
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int ret; |
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dprintk("NFS: nfs_readpages (%s/%Lu %d)\n", |
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inode->i_sb->s_id, |
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(unsigned long long)NFS_FILEID(inode), |
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nr_pages); |
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nfs_inc_stats(inode, NFSIOS_VFSREADPAGES); |
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ret = -ESTALE; |
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if (NFS_STALE(inode)) |
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goto out; |
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if (file == NULL) { |
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ret = -EBADF; |
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desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ); |
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if (desc.ctx == NULL) |
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goto out; |
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} else |
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desc.ctx = get_nfs_open_context(nfs_file_open_context(file)); |
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/* attempt to read as many of the pages as possible from the cache |
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* - this returns -ENOBUFS immediately if the cookie is negative |
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*/ |
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ret = nfs_readpages_from_fscache(desc.ctx, inode, mapping, |
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pages, &nr_pages); |
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if (ret == 0) |
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goto read_complete; /* all pages were read */ |
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nfs_pageio_init_read(&desc.pgio, inode, false, |
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&nfs_async_read_completion_ops); |
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ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc); |
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nfs_pageio_complete_read(&desc.pgio); |
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read_complete: |
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put_nfs_open_context(desc.ctx); |
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out: |
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return ret; |
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} |
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int __init nfs_init_readpagecache(void) |
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{ |
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nfs_rdata_cachep = kmem_cache_create("nfs_read_data", |
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sizeof(struct nfs_pgio_header), |
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0, SLAB_HWCACHE_ALIGN, |
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NULL); |
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if (nfs_rdata_cachep == NULL) |
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return -ENOMEM; |
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return 0; |
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} |
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void nfs_destroy_readpagecache(void) |
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{ |
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kmem_cache_destroy(nfs_rdata_cachep); |
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} |
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static const struct nfs_rw_ops nfs_rw_read_ops = { |
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.rw_alloc_header = nfs_readhdr_alloc, |
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.rw_free_header = nfs_readhdr_free, |
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.rw_done = nfs_readpage_done, |
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.rw_result = nfs_readpage_result, |
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.rw_initiate = nfs_initiate_read, |
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};
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