From eb497943fa215897f2f60fd28aa6fe52da27ca6c Mon Sep 17 00:00:00 2001 From: David Howells Date: Tue, 2 Nov 2021 08:29:55 +0000 Subject: 9p: Convert to using the netfs helper lib to do reads and caching 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 Link: https://lore.kernel.org/r/163584179557.4023316.11089762304657644342.stgit@warthog.procyon.org.uk # rebase on folio Signed-off-by: Dominique Martinet --- fs/9p/vfs_file.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) (limited to 'fs/9p/vfs_file.c') 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); -- cgit v1.2.3