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. Signed-off-by: David Howells <dhowells@xxxxxxxxxx> cc: Dominique Martinet <asmadeus@xxxxxxxxxxxxx> cc: v9fs-developer@xxxxxxxxxxxxxxxxxxxxx cc: linux-cachefs@xxxxxxxxxx Link: https://lore.kernel.org/r/163162772646.438332.16323773205855053535.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # rfc --- fs/9p/Kconfig | 1 fs/9p/cache.c | 137 ------------------------------------------- fs/9p/cache.h | 99 +------------------------------ fs/9p/v9fs.h | 9 +++ fs/9p/vfs_addr.c | 174 ++++++++++++++++++++++++------------------------------ fs/9p/vfs_file.c | 21 +++++-- 6 files changed, 108 insertions(+), 333 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 eb2151fb6049..68e5d12e690d 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 c7e74776ce90..cfafa89b972c 100644 --- a/fs/9p/cache.h +++ b/fs/9p/cache.h @@ -7,10 +7,11 @@ #ifndef _9P_CACHE_H #define _9P_CACHE_H -#ifdef CONFIG_9P_FSCACHE -#define FSCACHE_USE_OLD_IO_API + +#define FSCACHE_USE_NEW_IO_API #include <linux/fscache.h> -#include <linux/spinlock.h> + +#ifdef CONFIG_9P_FSCACHE extern struct fscache_netfs v9fs_cache_netfs; extern const struct fscache_cookie_def v9fs_cache_session_index_def; @@ -28,64 +29,6 @@ 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) @@ -100,39 +43,5 @@ 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..07332f135b38 100644 --- a/fs/9p/v9fs.h +++ b/fs/9p/v9fs.h @@ -123,6 +123,15 @@ 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); diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c index cce9ace651a2..a7e080916826 100644 --- a/fs/9p/vfs_addr.c +++ b/fs/9p/vfs_addr.c @@ -19,7 +19,7 @@ #include <linux/idr.h> #include <linux/sched.h> #include <linux/uio.h> -#include <linux/bvec.h> +#include <linux/netfs.h> #include <net/9p/9p.h> #include <net/9p/client.h> @@ -29,89 +29,82 @@ #include "fid.h" /** - * v9fs_fid_readpage - read an entire page in from 9P - * - * @fid: 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; + loff_t pos = subreq->start + subreq->transferred; + size_t len = subreq->len - subreq->transferred; int retval, err; - p9_debug(P9_DEBUG_VFS, "\n"); - - BUG_ON(!PageLocked(page)); + iov_iter_xarray(&to, READ, &rreq->mapping->i_pages, pos, len); - retval = v9fs_readpage_from_fscache(inode, page); - if (retval == 0) - return retval; + retval = p9_client_read(fid, pos, &to, &err); + if (retval) + subreq->error = retval; +} - iov_iter_bvec(&to, READ, &bvec, 1, PAGE_SIZE); +/** + * 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) +{ + rreq->netfs_priv = file->private_data; +} - retval = p9_client_read(fid, page_offset(page), &to, &err); - if (err) { - v9fs_uncache_page(inode, page); - retval = err; - goto done; - } +/** + * 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)); - zero_user(page, retval, PAGE_SIZE - retval); - flush_dcache_page(page); - SetPageUptodate(page); + return fscache_cookie_enabled(cookie) && !hlist_empty(&cookie->backing_objects); +} - v9fs_readpage_to_fscache(inode, page); - retval = 0; +/** + * 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)); -done: - unlock_page(page); - return retval; + return fscache_begin_read_operation(&rreq->cache_resources, 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, +}; + /** * v9fs_vfs_readpage - read an entire page in from 9P - * * @filp: 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); } /** @@ -124,7 +117,14 @@ 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_AFS_FSCACHE + if (PageFsCache(page)) { + if (!(gfp & __GFP_DIRECT_RECLAIM) || !(gfp & __GFP_FS)) + return 0; + wait_on_page_fscache(page); + } +#endif + return 1; } /** @@ -137,21 +137,16 @@ 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) @@ -159,17 +154,14 @@ 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; @@ -205,14 +197,13 @@ 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; } @@ -256,35 +247,24 @@ 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; } @@ -324,7 +304,7 @@ 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 aab5e6538660..4b617d10cf28 100644 --- a/fs/9p/vfs_file.c +++ b/fs/9p/vfs_file.c @@ -542,14 +542,27 @@ 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_V9FS_FSCACHE + if (PageFsCache(page) && + wait_on_page_bit_killable(page, PG_fscache) < 0) + return VM_FAULT_RETRY; +#endif + + if (PageWriteback(page) && + wait_on_page_bit_killable(page, PG_writeback) < 0) + return VM_FAULT_RETRY; + /* 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);
