From 2ff1e97587f4d398686f52c07afde3faf3da4e5c Mon Sep 17 00:00:00 2001 From: David Howells Date: Tue, 19 Mar 2024 10:00:09 +0000 Subject: netfs: Replace PG_fscache by setting folio->private and marking dirty When dirty data is being written to the cache, setting/waiting on/clearing the fscache flag is always done in tandem with setting/waiting on/clearing the writeback flag. The netfslib buffered write routines wait on and set both flags and the write request cleanup clears both flags, so the fscache flag is almost superfluous. The reason it isn't superfluous is because the fscache flag is also used to indicate that data just read from the server is being written to the cache. The flag is used to prevent a race involving overlapping direct-I/O writes to the cache. Change this to indicate that a page is in need of being copied to the cache by placing a magic value in folio->private and marking the folios dirty. Then when the writeback code sees a folio marked in this way, it only writes it to the cache and not to the server. If a folio that has this magic value set is modified, the value is just replaced and the folio will then be uplodaded too. With this, PG_fscache is no longer required by the netfslib core, 9p and afs. Ceph and nfs, however, still need to use the old PG_fscache-based tracking. To deal with this, a flag, NETFS_ICTX_USE_PGPRIV2, now has to be set on the flags in the netfs_inode struct for those filesystems. This reenables the use of PG_fscache in that inode. 9p and afs use the netfslib write helpers so get switched over; cifs, for the moment, does page-by-page manual access to the cache, so doesn't use PG_fscache and is unaffected. Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: Matthew Wilcox (Oracle) cc: Eric Van Hensbergen cc: Latchesar Ionkov cc: Dominique Martinet cc: Christian Schoenebeck cc: Marc Dionne cc: Ilya Dryomov cc: Xiubo Li cc: Steve French cc: Paulo Alcantara cc: Ronnie Sahlberg cc: Shyam Prasad N cc: Tom Talpey cc: Bharath SM cc: Trond Myklebust cc: Anna Schumaker cc: netfs@lists.linux.dev cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: ceph-devel@vger.kernel.org cc: linux-cifs@vger.kernel.org cc: linux-nfs@vger.kernel.org cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org --- fs/ceph/addr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/ceph/addr.c') diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c index ee9caf7916fb..28ae4976a4f9 100644 --- a/fs/ceph/addr.c +++ b/fs/ceph/addr.c @@ -517,7 +517,7 @@ static void ceph_fscache_write_to_cache(struct inode *inode, u64 off, u64 len, b struct fscache_cookie *cookie = ceph_fscache_cookie(ci); fscache_write_to_cache(cookie, inode->i_mapping, off, len, i_size_read(inode), - ceph_fscache_write_terminated, inode, caching); + ceph_fscache_write_terminated, inode, true, caching); } #else static inline void ceph_set_page_fscache(struct page *page) -- cgit