diff options
Diffstat (limited to 'kernel/fs/nfs/fscache.c')
| -rw-r--r-- | kernel/fs/nfs/fscache.c | 439 |
1 files changed, 439 insertions, 0 deletions
diff --git a/kernel/fs/nfs/fscache.c b/kernel/fs/nfs/fscache.c new file mode 100644 index 000000000..d63bea8bb --- /dev/null +++ b/kernel/fs/nfs/fscache.c @@ -0,0 +1,439 @@ +/* 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_inc_fscache_stats(page->mapping->host, + NFSIOS_FSCACHE_PAGES_UNCACHED); + } + + 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_inc_fscache_stats(page->mapping->host, + NFSIOS_FSCACHE_PAGES_UNCACHED); +} + +/* + * 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_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK); + return ret; + + case -ENOBUFS: /* inode not in cache */ + case -ENODATA: /* page not in cache */ + nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL); + dfprintk(FSCACHE, + "NFS: readpage_from_fscache %d\n", ret); + return 1; + + default: + dfprintk(FSCACHE, "NFS: readpage_from_fscache %d\n", ret); + nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL); + } + 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_inc_fscache_stats(inode, + NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL); + nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED); + } else { + nfs_inc_fscache_stats(inode, + NFSIOS_FSCACHE_PAGES_WRITTEN_OK); + } +} |