diff options
| -rw-r--r-- | fs/btrfs/inode.c | 34 |
1 files changed, 26 insertions, 8 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index c4b68be7edd7..a240b7fff984 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -7532,17 +7532,35 @@ static int btrfs_dio_iomap_begin(struct inode *inode, loff_t start, lockend = start + len - 1; /* - * The generic stuff only does filemap_write_and_wait_range, which - * isn't enough if we've written compressed pages to this area, so we - * need to flush the dirty pages again to make absolutely sure that any - * outstanding dirty pages are on disk. + * iomap_dio_rw() only does filemap_write_and_wait_range(), which isn't + * enough if we've written compressed pages to this area, so we need to + * flush the dirty pages again to make absolutely sure that any + * outstanding dirty pages are on disk - the first flush only starts + * compression on the data, while keeping the pages locked, so by the + * time the second flush returns we know bios for the compressed pages + * were submitted and finished, and the pages no longer under writeback. + * + * If we have a NOWAIT request and we have any pages in the range that + * are locked, likely due to compression still in progress, we don't want + * to block on page locks. We also don't want to block on pages marked as + * dirty or under writeback (same as for the non-compression case). + * iomap_dio_rw() did the same check, but after that and before we got + * here, mmap'ed writes may have happened or buffered reads started + * (readpage() and readahead(), which lock pages), as we haven't locked + * the file range yet. */ if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT, &BTRFS_I(inode)->runtime_flags)) { - ret = filemap_fdatawrite_range(inode->i_mapping, start, - start + length - 1); - if (ret) - return ret; + if (flags & IOMAP_NOWAIT) { + if (filemap_range_needs_writeback(inode->i_mapping, + lockstart, lockend)) + return -EAGAIN; + } else { + ret = filemap_fdatawrite_range(inode->i_mapping, start, + start + length - 1); + if (ret) + return ret; + } } dio_data = kzalloc(sizeof(*dio_data), GFP_NOFS); |