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Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH v3 2/6] 9p: Convert to using the netfs helper lib to do reads and caching From: David Howells To: "Matthew Wilcox (Oracle)" Cc: v9fs-developer@lists.sourceforge.net, linux-cachefs@redhat.com, dhowells@redhat.com, Jeff Layton , Ilya Dryomov , Dominique Martinet , linux-fsdevel@vger.kernel.org, linux-cachefs@redhat.com, v9fs-developer@lists.sourceforge.net, linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, devel@lists.orangefs.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Date: Tue, 02 Nov 2021 08:29:55 +0000 Message-ID: <163584179557.4023316.11089762304657644342.stgit@warthog.procyon.org.uk> In-Reply-To: <163584174921.4023316.8927114426959755223.stgit@warthog.procyon.org.uk> References: <163584174921.4023316.8927114426959755223.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.23 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org Convert the 9p filesystem to use the netfs helper lib to handle readpage, readahead and write_begin, converting those into a common issue_op for the filesystem itself to handle. The netfs helper lib also handles reading from fscache if a cache is available, and interleaving reads from both sources. This change also switches from the old fscache I/O API to the new one, meaning that fscache no longer keeps track of netfs pages and instead does async DIO between the backing files and the 9p file pagecache. As a part of this change, the handling of PG_fscache changes. It now just means that the cache has a write I/O operation in progress on a page (PG_locked is used for a read I/O op). Note that this is a cut-down version of the fscache rewrite and does not change any of the cookie and cache coherency handling. Changes ======= ver #4: - Rebase on top of folios. - Don't use wait_on_page_bit_killable(). ver #3: - v9fs_req_issue_op() needs to terminate the subrequest. - v9fs_write_end() needs to call SetPageUptodate() a bit more often. - It's not CONFIG_{AFS,V9FS}_FSCACHE[1] - v9fs_init_rreq() should take a ref on the p9_fid and the cleanup should drop it [from Dominique Martinet]. Signed-off-by: David Howells Reviewed-and-tested-by: Dominique Martinet cc: v9fs-developer@lists.sourceforge.net cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/YUm+xucHxED+1MJp@codewreck.org/ [1] Link: https://lore.kernel.org/r/163162772646.438332.16323773205855053535.stgit@warthog.procyon.org.uk/ # rfc Link: https://lore.kernel.org/r/163189109885.2509237.7153668924503399173.stgit@warthog.procyon.org.uk/ # rfc v2 Link: https://lore.kernel.org/r/163363943896.1980952.1226527304649419689.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/163551662876.1877519.14706391695553204156.stgit@warthog.procyon.org.uk/ # v4 --- fs/9p/Kconfig | 1 fs/9p/cache.c | 137 -------------------------------------- fs/9p/cache.h | 97 +-------------------------- fs/9p/v9fs.h | 9 ++ fs/9p/vfs_addr.c | 195 +++++++++++++++++++++++++++--------------------------- fs/9p/vfs_file.c | 17 ++++- 6 files changed, 122 insertions(+), 334 deletions(-) diff --git a/fs/9p/Kconfig b/fs/9p/Kconfig index 09fd4a185fd2..d7bc93447c85 100644 --- a/fs/9p/Kconfig +++ b/fs/9p/Kconfig @@ -2,6 +2,7 @@ config 9P_FS tristate "Plan 9 Resource Sharing Support (9P2000)" depends on INET && NET_9P + select NETFS_SUPPORT help If you say Y here, you will get experimental support for Plan 9 resource sharing via the 9P2000 protocol. diff --git a/fs/9p/cache.c b/fs/9p/cache.c index 1769a44f4819..077f0a40aa01 100644 --- a/fs/9p/cache.c +++ b/fs/9p/cache.c @@ -199,140 +199,3 @@ void v9fs_cache_inode_reset_cookie(struct inode *inode) mutex_unlock(&v9inode->fscache_lock); } - -int __v9fs_fscache_release_page(struct page *page, gfp_t gfp) -{ - struct inode *inode = page->mapping->host; - struct v9fs_inode *v9inode = V9FS_I(inode); - - BUG_ON(!v9inode->fscache); - - return fscache_maybe_release_page(v9inode->fscache, page, gfp); -} - -void __v9fs_fscache_invalidate_page(struct page *page) -{ - struct inode *inode = page->mapping->host; - struct v9fs_inode *v9inode = V9FS_I(inode); - - BUG_ON(!v9inode->fscache); - - if (PageFsCache(page)) { - fscache_wait_on_page_write(v9inode->fscache, page); - BUG_ON(!PageLocked(page)); - fscache_uncache_page(v9inode->fscache, page); - } -} - -static void v9fs_vfs_readpage_complete(struct page *page, void *data, - int error) -{ - if (!error) - SetPageUptodate(page); - - unlock_page(page); -} - -/* - * __v9fs_readpage_from_fscache - read a page from cache - * - * Returns 0 if the pages are in cache and a BIO is submitted, - * 1 if the pages are not in cache and -error otherwise. - */ - -int __v9fs_readpage_from_fscache(struct inode *inode, struct page *page) -{ - int ret; - const struct v9fs_inode *v9inode = V9FS_I(inode); - - p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page); - if (!v9inode->fscache) - return -ENOBUFS; - - ret = fscache_read_or_alloc_page(v9inode->fscache, - page, - v9fs_vfs_readpage_complete, - NULL, - GFP_KERNEL); - switch (ret) { - case -ENOBUFS: - case -ENODATA: - p9_debug(P9_DEBUG_FSC, "page/inode not in cache %d\n", ret); - return 1; - case 0: - p9_debug(P9_DEBUG_FSC, "BIO submitted\n"); - return ret; - default: - p9_debug(P9_DEBUG_FSC, "ret %d\n", ret); - return ret; - } -} - -/* - * __v9fs_readpages_from_fscache - read multiple pages from cache - * - * Returns 0 if the pages are in cache and a BIO is submitted, - * 1 if the pages are not in cache and -error otherwise. - */ - -int __v9fs_readpages_from_fscache(struct inode *inode, - struct address_space *mapping, - struct list_head *pages, - unsigned *nr_pages) -{ - int ret; - const struct v9fs_inode *v9inode = V9FS_I(inode); - - p9_debug(P9_DEBUG_FSC, "inode %p pages %u\n", inode, *nr_pages); - if (!v9inode->fscache) - return -ENOBUFS; - - ret = fscache_read_or_alloc_pages(v9inode->fscache, - mapping, pages, nr_pages, - v9fs_vfs_readpage_complete, - NULL, - mapping_gfp_mask(mapping)); - switch (ret) { - case -ENOBUFS: - case -ENODATA: - p9_debug(P9_DEBUG_FSC, "pages/inodes not in cache %d\n", ret); - return 1; - case 0: - BUG_ON(!list_empty(pages)); - BUG_ON(*nr_pages != 0); - p9_debug(P9_DEBUG_FSC, "BIO submitted\n"); - return ret; - default: - p9_debug(P9_DEBUG_FSC, "ret %d\n", ret); - return ret; - } -} - -/* - * __v9fs_readpage_to_fscache - write a page to the cache - * - */ - -void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page) -{ - int ret; - const struct v9fs_inode *v9inode = V9FS_I(inode); - - p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page); - ret = fscache_write_page(v9inode->fscache, page, - i_size_read(&v9inode->vfs_inode), GFP_KERNEL); - p9_debug(P9_DEBUG_FSC, "ret = %d\n", ret); - if (ret != 0) - v9fs_uncache_page(inode, page); -} - -/* - * wait for a page to complete writing to the cache - */ -void __v9fs_fscache_wait_on_page_write(struct inode *inode, struct page *page) -{ - const struct v9fs_inode *v9inode = V9FS_I(inode); - p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page); - if (PageFsCache(page)) - fscache_wait_on_page_write(v9inode->fscache, page); -} diff --git a/fs/9p/cache.h b/fs/9p/cache.h index 00f107af443e..7480b4b49fea 100644 --- a/fs/9p/cache.h +++ b/fs/9p/cache.h @@ -7,9 +7,10 @@ #ifndef _9P_CACHE_H #define _9P_CACHE_H -#ifdef CONFIG_9P_FSCACHE +#define FSCACHE_USE_NEW_IO_API #include -#include + +#ifdef CONFIG_9P_FSCACHE extern struct fscache_netfs v9fs_cache_netfs; extern const struct fscache_cookie_def v9fs_cache_session_index_def; @@ -27,64 +28,6 @@ extern void v9fs_cache_inode_reset_cookie(struct inode *inode); extern int __v9fs_cache_register(void); extern void __v9fs_cache_unregister(void); -extern int __v9fs_fscache_release_page(struct page *page, gfp_t gfp); -extern void __v9fs_fscache_invalidate_page(struct page *page); -extern int __v9fs_readpage_from_fscache(struct inode *inode, - struct page *page); -extern int __v9fs_readpages_from_fscache(struct inode *inode, - struct address_space *mapping, - struct list_head *pages, - unsigned *nr_pages); -extern void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page); -extern void __v9fs_fscache_wait_on_page_write(struct inode *inode, - struct page *page); - -static inline int v9fs_fscache_release_page(struct page *page, - gfp_t gfp) -{ - return __v9fs_fscache_release_page(page, gfp); -} - -static inline void v9fs_fscache_invalidate_page(struct page *page) -{ - __v9fs_fscache_invalidate_page(page); -} - -static inline int v9fs_readpage_from_fscache(struct inode *inode, - struct page *page) -{ - return __v9fs_readpage_from_fscache(inode, page); -} - -static inline int v9fs_readpages_from_fscache(struct inode *inode, - struct address_space *mapping, - struct list_head *pages, - unsigned *nr_pages) -{ - return __v9fs_readpages_from_fscache(inode, mapping, pages, - nr_pages); -} - -static inline void v9fs_readpage_to_fscache(struct inode *inode, - struct page *page) -{ - if (PageFsCache(page)) - __v9fs_readpage_to_fscache(inode, page); -} - -static inline void v9fs_uncache_page(struct inode *inode, struct page *page) -{ - struct v9fs_inode *v9inode = V9FS_I(inode); - fscache_uncache_page(v9inode->fscache, page); - BUG_ON(PageFsCache(page)); -} - -static inline void v9fs_fscache_wait_on_page_write(struct inode *inode, - struct page *page) -{ - return __v9fs_fscache_wait_on_page_write(inode, page); -} - #else /* CONFIG_9P_FSCACHE */ static inline void v9fs_cache_inode_get_cookie(struct inode *inode) @@ -99,39 +42,5 @@ static inline void v9fs_cache_inode_set_cookie(struct inode *inode, struct file { } -static inline int v9fs_fscache_release_page(struct page *page, - gfp_t gfp) { - return 1; -} - -static inline void v9fs_fscache_invalidate_page(struct page *page) {} - -static inline int v9fs_readpage_from_fscache(struct inode *inode, - struct page *page) -{ - return -ENOBUFS; -} - -static inline int v9fs_readpages_from_fscache(struct inode *inode, - struct address_space *mapping, - struct list_head *pages, - unsigned *nr_pages) -{ - return -ENOBUFS; -} - -static inline void v9fs_readpage_to_fscache(struct inode *inode, - struct page *page) -{} - -static inline void v9fs_uncache_page(struct inode *inode, struct page *page) -{} - -static inline void v9fs_fscache_wait_on_page_write(struct inode *inode, - struct page *page) -{ - return; -} - #endif /* CONFIG_9P_FSCACHE */ #endif /* _9P_CACHE_H */ diff --git a/fs/9p/v9fs.h b/fs/9p/v9fs.h index 4ca56c5dd637..92124b235a6d 100644 --- a/fs/9p/v9fs.h +++ b/fs/9p/v9fs.h @@ -124,6 +124,15 @@ static inline struct v9fs_inode *V9FS_I(const struct inode *inode) return container_of(inode, struct v9fs_inode, vfs_inode); } +static inline struct fscache_cookie *v9fs_inode_cookie(struct v9fs_inode *v9inode) +{ +#ifdef CONFIG_9P_FSCACHE + return v9inode->fscache; +#else + return NULL; +#endif +} + extern int v9fs_show_options(struct seq_file *m, struct dentry *root); struct p9_fid *v9fs_session_init(struct v9fs_session_info *, const char *, diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c index 1c4f1b39cc95..2a2368d83868 100644 --- a/fs/9p/vfs_addr.c +++ b/fs/9p/vfs_addr.c @@ -19,7 +19,7 @@ #include #include #include -#include +#include #include #include @@ -29,88 +29,97 @@ #include "fid.h" /** - * v9fs_fid_readpage - read an entire page in from 9P - * @data: Opaque pointer to the fid being read - * @page: structure to page - * + * v9fs_req_issue_op - Issue a read from 9P + * @subreq: The read to make */ -static int v9fs_fid_readpage(void *data, struct page *page) +static void v9fs_req_issue_op(struct netfs_read_subrequest *subreq) { - struct p9_fid *fid = data; - struct inode *inode = page->mapping->host; - struct bio_vec bvec = {.bv_page = page, .bv_len = PAGE_SIZE}; + struct netfs_read_request *rreq = subreq->rreq; + struct p9_fid *fid = rreq->netfs_priv; struct iov_iter to; - int retval, err; + loff_t pos = subreq->start + subreq->transferred; + size_t len = subreq->len - subreq->transferred; + int total, err; - p9_debug(P9_DEBUG_VFS, "\n"); + iov_iter_xarray(&to, READ, &rreq->mapping->i_pages, pos, len); - BUG_ON(!PageLocked(page)); + total = p9_client_read(fid, pos, &to, &err); + netfs_subreq_terminated(subreq, err ?: total, false); +} - retval = v9fs_readpage_from_fscache(inode, page); - if (retval == 0) - return retval; +/** + * v9fs_init_rreq - Initialise a read request + * @rreq: The read request + * @file: The file being read from + */ +static void v9fs_init_rreq(struct netfs_read_request *rreq, struct file *file) +{ + struct p9_fid *fid = file->private_data; - iov_iter_bvec(&to, READ, &bvec, 1, PAGE_SIZE); + refcount_inc(&fid->count); + rreq->netfs_priv = fid; +} - retval = p9_client_read(fid, page_offset(page), &to, &err); - if (err) { - v9fs_uncache_page(inode, page); - retval = err; - goto done; - } +/** + * v9fs_req_cleanup - Cleanup request initialized by v9fs_init_rreq + * @mapping: unused mapping of request to cleanup + * @priv: private data to cleanup, a fid, guaranted non-null. + */ +static void v9fs_req_cleanup(struct address_space *mapping, void *priv) +{ + struct p9_fid *fid = priv; - zero_user(page, retval, PAGE_SIZE - retval); - flush_dcache_page(page); - SetPageUptodate(page); + p9_client_clunk(fid); +} - v9fs_readpage_to_fscache(inode, page); - retval = 0; +/** + * v9fs_is_cache_enabled - Determine if caching is enabled for an inode + * @inode: The inode to check + */ +static bool v9fs_is_cache_enabled(struct inode *inode) +{ + struct fscache_cookie *cookie = v9fs_inode_cookie(V9FS_I(inode)); -done: - unlock_page(page); - return retval; + return fscache_cookie_enabled(cookie) && !hlist_empty(&cookie->backing_objects); +} + +/** + * v9fs_begin_cache_operation - Begin a cache operation for a read + * @rreq: The read request + */ +static int v9fs_begin_cache_operation(struct netfs_read_request *rreq) +{ + struct fscache_cookie *cookie = v9fs_inode_cookie(V9FS_I(rreq->inode)); + + return fscache_begin_read_operation(rreq, cookie); } +static const struct netfs_read_request_ops v9fs_req_ops = { + .init_rreq = v9fs_init_rreq, + .is_cache_enabled = v9fs_is_cache_enabled, + .begin_cache_operation = v9fs_begin_cache_operation, + .issue_op = v9fs_req_issue_op, + .cleanup = v9fs_req_cleanup, +}; + /** * v9fs_vfs_readpage - read an entire page in from 9P - * - * @filp: file being read + * @file: file being read * @page: structure to page * */ - -static int v9fs_vfs_readpage(struct file *filp, struct page *page) +static int v9fs_vfs_readpage(struct file *file, struct page *page) { - return v9fs_fid_readpage(filp->private_data, page); + return netfs_readpage(file, page, &v9fs_req_ops, NULL); } /** - * v9fs_vfs_readpages - read a set of pages from 9P - * - * @filp: file being read - * @mapping: the address space - * @pages: list of pages to read - * @nr_pages: count of pages to read - * + * v9fs_vfs_readahead - read a set of pages from 9P + * @ractl: The readahead parameters */ - -static int v9fs_vfs_readpages(struct file *filp, struct address_space *mapping, - struct list_head *pages, unsigned nr_pages) +static void v9fs_vfs_readahead(struct readahead_control *ractl) { - int ret = 0; - struct inode *inode; - - inode = mapping->host; - p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp); - - ret = v9fs_readpages_from_fscache(inode, mapping, pages, &nr_pages); - if (ret == 0) - return ret; - - ret = read_cache_pages(mapping, pages, v9fs_fid_readpage, - filp->private_data); - p9_debug(P9_DEBUG_VFS, " = %d\n", ret); - return ret; + netfs_readahead(ractl, &v9fs_req_ops, NULL); } /** @@ -125,7 +134,14 @@ static int v9fs_release_page(struct page *page, gfp_t gfp) { if (PagePrivate(page)) return 0; - return v9fs_fscache_release_page(page, gfp); +#ifdef CONFIG_9P_FSCACHE + if (PageFsCache(page)) { + if (!(gfp & __GFP_DIRECT_RECLAIM) || !(gfp & __GFP_FS)) + return 0; + wait_on_page_fscache(page); + } +#endif + return 1; } /** @@ -138,21 +154,16 @@ static int v9fs_release_page(struct page *page, gfp_t gfp) static void v9fs_invalidate_page(struct page *page, unsigned int offset, unsigned int length) { - /* - * If called with zero offset, we should release - * the private state assocated with the page - */ - if (offset == 0 && length == PAGE_SIZE) - v9fs_fscache_invalidate_page(page); + wait_on_page_fscache(page); } static int v9fs_vfs_writepage_locked(struct page *page) { struct inode *inode = page->mapping->host; struct v9fs_inode *v9inode = V9FS_I(inode); + loff_t start = page_offset(page); loff_t size = i_size_read(inode); struct iov_iter from; - struct bio_vec bvec; int err, len; if (page->index == size >> PAGE_SHIFT) @@ -160,17 +171,14 @@ static int v9fs_vfs_writepage_locked(struct page *page) else len = PAGE_SIZE; - bvec.bv_page = page; - bvec.bv_offset = 0; - bvec.bv_len = len; - iov_iter_bvec(&from, WRITE, &bvec, 1, len); + iov_iter_xarray(&from, WRITE, &page->mapping->i_pages, start, len); /* We should have writeback_fid always set */ BUG_ON(!v9inode->writeback_fid); set_page_writeback(page); - p9_client_write(v9inode->writeback_fid, page_offset(page), &from, &err); + p9_client_write(v9inode->writeback_fid, start, &from, &err); end_page_writeback(page); return err; @@ -208,14 +216,13 @@ static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc) static int v9fs_launder_page(struct page *page) { int retval; - struct inode *inode = page->mapping->host; - v9fs_fscache_wait_on_page_write(inode, page); if (clear_page_dirty_for_io(page)) { retval = v9fs_vfs_writepage_locked(page); if (retval) return retval; } + wait_on_page_fscache(page); return 0; } @@ -260,35 +267,24 @@ static int v9fs_write_begin(struct file *filp, struct address_space *mapping, loff_t pos, unsigned len, unsigned flags, struct page **pagep, void **fsdata) { - int retval = 0; + int retval; struct page *page; - struct v9fs_inode *v9inode; - pgoff_t index = pos >> PAGE_SHIFT; - struct inode *inode = mapping->host; - + struct v9fs_inode *v9inode = V9FS_I(mapping->host); p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); - v9inode = V9FS_I(inode); -start: - page = grab_cache_page_write_begin(mapping, index, flags); - if (!page) { - retval = -ENOMEM; - goto out; - } BUG_ON(!v9inode->writeback_fid); - if (PageUptodate(page)) - goto out; - if (len == PAGE_SIZE) - goto out; + /* Prefetch area to be written into the cache if we're caching this + * file. We need to do this before we get a lock on the page in case + * there's more than one writer competing for the same cache block. + */ + retval = netfs_write_begin(filp, mapping, pos, len, flags, &page, fsdata, + &v9fs_req_ops, NULL); + if (retval < 0) + return retval; - retval = v9fs_fid_readpage(v9inode->writeback_fid, page); - put_page(page); - if (!retval) - goto start; -out: - *pagep = page; + *pagep = find_subpage(page, pos / PAGE_SIZE); return retval; } @@ -305,10 +301,11 @@ static int v9fs_write_end(struct file *filp, struct address_space *mapping, if (unlikely(copied < len)) { copied = 0; goto out; - } else if (len == PAGE_SIZE) { - SetPageUptodate(page); } + + SetPageUptodate(page); } + /* * No need to use i_size_read() here, the i_size * cannot change under us because we hold the i_mutex. @@ -328,7 +325,7 @@ static int v9fs_write_end(struct file *filp, struct address_space *mapping, const struct address_space_operations v9fs_addr_operations = { .readpage = v9fs_vfs_readpage, - .readpages = v9fs_vfs_readpages, + .readahead = v9fs_vfs_readahead, .set_page_dirty = __set_page_dirty_nobuffers, .writepage = v9fs_vfs_writepage, .write_begin = v9fs_write_begin, diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c index 246235ebdb70..8d5e0ef5518e 100644 --- a/fs/9p/vfs_file.c +++ b/fs/9p/vfs_file.c @@ -537,14 +537,23 @@ v9fs_vm_page_mkwrite(struct vm_fault *vmf) p9_debug(P9_DEBUG_VFS, "page %p fid %lx\n", page, (unsigned long)filp->private_data); + v9inode = V9FS_I(inode); + + /* Wait for the page to be written to the cache before we allow it to + * be modified. We then assume the entire page will need writing back. + */ +#ifdef CONFIG_9P_FSCACHE + if (PageFsCache(page) && + wait_on_page_fscache_killable(page) < 0) + return VM_FAULT_RETRY; +#endif + /* Update file times before taking page lock */ file_update_time(filp); - v9inode = V9FS_I(inode); - /* make sure the cache has finished storing the page */ - v9fs_fscache_wait_on_page_write(inode, page); BUG_ON(!v9inode->writeback_fid); - lock_page(page); + if (lock_page_killable(page) < 0) + return VM_FAULT_RETRY; if (page->mapping != inode->i_mapping) goto out_unlock; wait_for_stable_page(page);