/* NFS filesystem cache interface * * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public Licence * as published by the Free Software Foundation; either version * 2 of the Licence, or (at your option) any later version. */ #include <linux/init.h> #include <linux/kernel.h> #include <linux/sched.h> #include <linux/mm.h> #include <linux/nfs_fs.h> #include <linux/nfs_fs_sb.h> #include <linux/in6.h> #include <linux/seq_file.h> #include <linux/slab.h> #include "internal.h" #include "iostat.h" #include "fscache.h" #define NFSDBG_FACILITY NFSDBG_FSCACHE static struct rb_root nfs_fscache_keys = RB_ROOT; static DEFINE_SPINLOCK(nfs_fscache_keys_lock); /* * Get the per-client index cookie for an NFS client if the appropriate mount * flag was set * - We always try and get an index cookie for the client, but get filehandle * cookies on a per-superblock basis, depending on the mount flags */ void nfs_fscache_get_client_cookie(struct nfs_client *clp) { /* create a cache index for looking up filehandles */ clp->fscache = fscache_acquire_cookie(nfs_fscache_netfs.primary_index, &nfs_fscache_server_index_def, clp, true); dfprintk(FSCACHE, "NFS: get client cookie (0x%p/0x%p)\n", clp, clp->fscache); } /* * Dispose of a per-client cookie */ void nfs_fscache_release_client_cookie(struct nfs_client *clp) { dfprintk(FSCACHE, "NFS: releasing client cookie (0x%p/0x%p)\n", clp, clp->fscache); fscache_relinquish_cookie(clp->fscache, 0); clp->fscache = NULL; } /* * Get the cache cookie for an NFS superblock. We have to handle * uniquification here because the cache doesn't do it for us. * * The default uniquifier is just an empty string, but it may be overridden * either by the 'fsc=xxx' option to mount, or by inheriting it from the parent * superblock across an automount point of some nature. */ void nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq, int ulen) { struct nfs_fscache_key *key, *xkey; struct nfs_server *nfss = NFS_SB(sb); struct rb_node **p, *parent; int diff; if (!uniq) { uniq = ""; ulen = 1; } key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL); if (!key) return; key->nfs_client = nfss->nfs_client; key->key.super.s_flags = sb->s_flags & NFS_MS_MASK; key->key.nfs_server.flags = nfss->flags; key->key.nfs_server.rsize = nfss->rsize; key->key.nfs_server.wsize = nfss->wsize; key->key.nfs_server.acregmin = nfss->acregmin; key->key.nfs_server.acregmax = nfss->acregmax; key->key.nfs_server.acdirmin = nfss->acdirmin; key->key.nfs_server.acdirmax = nfss->acdirmax; key->key.nfs_server.fsid = nfss->fsid; key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor; key->key.uniq_len = ulen; memcpy(key->key.uniquifier, uniq, ulen); spin_lock(&nfs_fscache_keys_lock); p = &nfs_fscache_keys.rb_node; parent = NULL; while (*p) { parent = *p; xkey = rb_entry(parent, struct nfs_fscache_key, node); if (key->nfs_client < xkey->nfs_client) goto go_left; if (key->nfs_client > xkey->nfs_client) goto go_right; diff = memcmp(&key->key, &xkey->key, sizeof(key->key)); if (diff < 0) goto go_left; if (diff > 0) goto go_right; if (key->key.uniq_len == 0) goto non_unique; diff = memcmp(key->key.uniquifier, xkey->key.uniquifier, key->key.uniq_len); if (diff < 0) goto go_left; if (diff > 0) goto go_right; goto non_unique; go_left: p = &(*p)->rb_left; continue; go_right: p = &(*p)->rb_right; } rb_link_node(&key->node, parent, p); rb_insert_color(&key->node, &nfs_fscache_keys); spin_unlock(&nfs_fscache_keys_lock); nfss->fscache_key = key; /* create a cache index for looking up filehandles */ nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache, &nfs_fscache_super_index_def, nfss, true); dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n", nfss, nfss->fscache); return; non_unique: spin_unlock(&nfs_fscache_keys_lock); kfree(key); nfss->fscache_key = NULL; nfss->fscache = NULL; printk(KERN_WARNING "NFS:" " Cache request denied due to non-unique superblock keys\n"); } /* * release a per-superblock cookie */ void nfs_fscache_release_super_cookie(struct super_block *sb) { struct nfs_server *nfss = NFS_SB(sb); dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n", nfss, nfss->fscache); fscache_relinquish_cookie(nfss->fscache, 0); nfss->fscache = NULL; if (nfss->fscache_key) { spin_lock(&nfs_fscache_keys_lock); rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys); spin_unlock(&nfs_fscache_keys_lock); kfree(nfss->fscache_key); nfss->fscache_key = NULL; } } /* * Initialise the per-inode cache cookie pointer for an NFS inode. */ void nfs_fscache_init_inode(struct inode *inode) { struct nfs_inode *nfsi = NFS_I(inode); nfsi->fscache = NULL; if (!S_ISREG(inode->i_mode)) return; nfsi->fscache = fscache_acquire_cookie(NFS_SB(inode->i_sb)->fscache, &nfs_fscache_inode_object_def, nfsi, false); } /* * Release a per-inode cookie. */ void nfs_fscache_clear_inode(struct inode *inode) { struct nfs_inode *nfsi = NFS_I(inode); struct fscache_cookie *cookie = nfs_i_fscache(inode); dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n", nfsi, cookie); fscache_relinquish_cookie(cookie, false); nfsi->fscache = NULL; } static bool nfs_fscache_can_enable(void *data) { struct inode *inode = data; return !inode_is_open_for_write(inode); } /* * Enable or disable caching for a file that is being opened as appropriate. * The cookie is allocated when the inode is initialised, but is not enabled at * that time. Enablement is deferred to file-open time to avoid stat() and * access() thrashing the cache. * * For now, with NFS, only regular files that are open read-only will be able * to use the cache. * * We enable the cache for an inode if we open it read-only and it isn't * currently open for writing. We disable the cache if the inode is open * write-only. * * The caller uses the file struct to pin i_writecount on the inode before * calling us when a file is opened for writing, so we can make use of that. * * Note that this may be invoked multiple times in parallel by parallel * nfs_open() functions. */ void nfs_fscache_open_file(struct inode *inode, struct file *filp) { struct nfs_inode *nfsi = NFS_I(inode); struct fscache_cookie *cookie = nfs_i_fscache(inode); if (!fscache_cookie_valid(cookie)) return; if (inode_is_open_for_write(inode)) { dfprintk(FSCACHE, "NFS: nfsi 0x%p disabling cache\n", nfsi); clear_bit(NFS_INO_FSCACHE, &nfsi->flags); fscache_disable_cookie(cookie, true); fscache_uncache_all_inode_pages(cookie, inode); } else { dfprintk(FSCACHE, "NFS: nfsi 0x%p enabling cache\n", nfsi); fscache_enable_cookie(cookie, nfs_fscache_can_enable, inode); if (fscache_cookie_enabled(cookie)) set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags); } } EXPORT_SYMBOL_GPL(nfs_fscache_open_file); /* * Release the caching state associated with a page, if the page isn't busy * interacting with the cache. * - Returns true (can release page) or false (page busy). */ int nfs_fscache_release_page(struct page *page, gfp_t gfp) { if (PageFsCache(page)) { struct fscache_cookie *cookie = nfs_i_fscache(page->mapping->host); BUG_ON(!cookie); dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n", cookie, page, NFS_I(page->mapping->host)); if (!fscache_maybe_release_page(cookie, page, gfp)) return 0; nfs_add_fscache_stats(page->mapping->host, NFSIOS_FSCACHE_PAGES_UNCACHED, 1); } return 1; } /* * Release the caching state associated with a page if undergoing complete page * invalidation. */ void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode) { struct fscache_cookie *cookie = nfs_i_fscache(inode); BUG_ON(!cookie); dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n", cookie, page, NFS_I(inode)); fscache_wait_on_page_write(cookie, page); BUG_ON(!PageLocked(page)); fscache_uncache_page(cookie, page); nfs_add_fscache_stats(page->mapping->host, NFSIOS_FSCACHE_PAGES_UNCACHED, 1); } /* * Handle completion of a page being read from the cache. * - Called in process (keventd) context. */ static void nfs_readpage_from_fscache_complete(struct page *page, void *context, int error) { dfprintk(FSCACHE, "NFS: readpage_from_fscache_complete (0x%p/0x%p/%d)\n", page, context, error); /* if the read completes with an error, we just unlock the page and let * the VM reissue the readpage */ if (!error) { SetPageUptodate(page); unlock_page(page); } else { error = nfs_readpage_async(context, page->mapping->host, page); if (error) unlock_page(page); } } /* * Retrieve a page from fscache */ int __nfs_readpage_from_fscache(struct nfs_open_context *ctx, struct inode *inode, struct page *page) { int ret; dfprintk(FSCACHE, "NFS: readpage_from_fscache(fsc:%p/p:%p(i:%lx f:%lx)/0x%p)\n", nfs_i_fscache(inode), page, page->index, page->flags, inode); ret = fscache_read_or_alloc_page(nfs_i_fscache(inode), page, nfs_readpage_from_fscache_complete, ctx, GFP_KERNEL); switch (ret) { case 0: /* read BIO submitted (page in fscache) */ dfprintk(FSCACHE, "NFS: readpage_from_fscache: BIO submitted\n"); nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK, 1); return ret; case -ENOBUFS: /* inode not in cache */ case -ENODATA: /* page not in cache */ nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1); dfprintk(FSCACHE, "NFS: readpage_from_fscache %d\n", ret); return 1; default: dfprintk(FSCACHE, "NFS: readpage_from_fscache %d\n", ret); nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1); } return ret; } /* * Retrieve a set of pages from fscache */ int __nfs_readpages_from_fscache(struct nfs_open_context *ctx, struct inode *inode, struct address_space *mapping, struct list_head *pages, unsigned *nr_pages) { unsigned npages = *nr_pages; int ret; dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n", nfs_i_fscache(inode), npages, inode); ret = fscache_read_or_alloc_pages(nfs_i_fscache(inode), mapping, pages, nr_pages, nfs_readpage_from_fscache_complete, ctx, mapping_gfp_mask(mapping)); if (*nr_pages < npages) nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK, npages); if (*nr_pages > 0) nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, *nr_pages); switch (ret) { case 0: /* read submitted to the cache for all pages */ BUG_ON(!list_empty(pages)); BUG_ON(*nr_pages != 0); dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache: submitted\n"); return ret; case -ENOBUFS: /* some pages aren't cached and can't be */ case -ENODATA: /* some pages aren't cached */ dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache: no page: %d\n", ret); return 1; default: dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache: ret %d\n", ret); } return ret; } /* * Store a newly fetched page in fscache * - PG_fscache must be set on the page */ void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync) { int ret; dfprintk(FSCACHE, "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n", nfs_i_fscache(inode), page, page->index, page->flags, sync); ret = fscache_write_page(nfs_i_fscache(inode), page, GFP_KERNEL); dfprintk(FSCACHE, "NFS: readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n", page, page->index, page->flags, ret); if (ret != 0) { fscache_uncache_page(nfs_i_fscache(inode), page); nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL, 1); nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED, 1); } else { nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_WRITTEN_OK, 1); } }