Fix netfs_write_single() and afs_single_writepages() to better handle a write that would be skipped due to lock contention and WB_SYNC_NONE by returning 1 from netfs_write_single() if it skipped and making afs_single_writepages() skip also. If a skip occurs, the inode must be re-marked as the VFS may have cleared the mark. This is really only theoretical for directories in netfs_write_single() as the only path to that is through afs_single_writepages() that takes the ->validate_lock around it, thereby serialising it. Fixes: 6dd80936618c ("afs: Use netfslib for directories") Signed-off-by: David Howells cc: Marc Dionne cc: linux-afs@lists.infradead.org cc: linux-fsdevel@vger.kernel.org --- fs/afs/dir.c | 11 ++++++++++- fs/netfs/write_issue.c | 7 ++++++- 2 files changed, 16 insertions(+), 2 deletions(-) diff --git a/fs/afs/dir.c b/fs/afs/dir.c index aaaa55878ffd..d1542a1a50bf 100644 --- a/fs/afs/dir.c +++ b/fs/afs/dir.c @@ -2206,7 +2206,14 @@ int afs_single_writepages(struct address_space *mapping, /* Need to lock to prevent the folio queue and folios from being thrown * away. */ - down_read(&dvnode->validate_lock); + if (!down_read_trylock(&dvnode->validate_lock)) { + if (wbc->sync_mode == WB_SYNC_NONE) { + /* The VFS will have undirtied the inode. */ + netfs_single_mark_inode_dirty(&dvnode->netfs.inode); + return 0; + } + down_read(&dvnode->validate_lock); + } if (is_dir ? test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) : @@ -2214,6 +2221,8 @@ int afs_single_writepages(struct address_space *mapping, iov_iter_folio_queue(&iter, ITER_SOURCE, dvnode->directory, 0, 0, i_size_read(&dvnode->netfs.inode)); ret = netfs_writeback_single(mapping, wbc, &iter); + if (ret == 1) + ret = 0; /* Skipped write due to lock conflict. */ } up_read(&dvnode->validate_lock); diff --git a/fs/netfs/write_issue.c b/fs/netfs/write_issue.c index 03961622996b..c03c7cc45e47 100644 --- a/fs/netfs/write_issue.c +++ b/fs/netfs/write_issue.c @@ -830,6 +830,9 @@ static int netfs_write_folio_single(struct netfs_io_request *wreq, * * Write a monolithic, non-pagecache object back to the server and/or * the cache. + * + * Return: 0 if successful; 1 if skipped due to lock conflict and WB_SYNC_NONE; + * or a negative error code. */ int netfs_writeback_single(struct address_space *mapping, struct writeback_control *wbc, @@ -846,8 +849,10 @@ int netfs_writeback_single(struct address_space *mapping, if (!mutex_trylock(&ictx->wb_lock)) { if (wbc->sync_mode == WB_SYNC_NONE) { + /* The VFS will have undirtied the inode. */ + netfs_single_mark_inode_dirty(&ictx->inode); netfs_stat(&netfs_n_wb_lock_skip); - return 0; + return 1; } netfs_stat(&netfs_n_wb_lock_wait); mutex_lock(&ictx->wb_lock);