On Tue, 7 Oct 2014 18:44:35 -0400, Wang Shilong wrote: > Steps to reproduce: > # mkfs.btrfs -f /dev/sdb > # mount -t btrfs /dev/sdb /mnt -o compress=lzo > # dd if=/dev/zero of=/mnt/data bs=$((33*4096)) count=1 > > after previous steps, inode will be detected as bad compression ratio, > and NOCOMPRESS flag will be set for that inode. > > Reason is that compress have a max limit pages every time(128K), if a > 132k write in, it will be splitted into two write(128k+4k), this bug > is a leftover for commit 68bb462d42a(Btrfs: don't compress for a small write) > > Fix this problem by checking every time before compression, if it is a > small write(<=blocksize), we bail out and fall into nocompression directly. > > Signed-off-by: Wang Shilong <wangshilong1991@xxxxxxxxx> Looks good. Reviewed-by: Miao Xie <miaox@xxxxxxxxxxxxxx> > --- > fs/btrfs/inode.c | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index 344a322..b78e90a 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -411,14 +411,6 @@ static noinline int compress_file_range(struct inode *inode, > (start > 0 || end + 1 < BTRFS_I(inode)->disk_i_size)) > btrfs_add_inode_defrag(NULL, inode); > > - /* > - * skip compression for a small file range(<=blocksize) that > - * isn't an inline extent, since it dosen't save disk space at all. > - */ > - if ((end - start + 1) <= blocksize && > - (start > 0 || end + 1 < BTRFS_I(inode)->disk_i_size)) > - goto cleanup_and_bail_uncompressed; > - > actual_end = min_t(u64, isize, end + 1); > again: > will_compress = 0; > @@ -440,6 +432,14 @@ again: > > total_compressed = actual_end - start; > > + /* > + * skip compression for a small file range(<=blocksize) that > + * isn't an inline extent, since it dosen't save disk space at all. > + */ > + if (total_compressed <= blocksize && > + (start > 0 || end + 1 < BTRFS_I(inode)->disk_i_size)) > + goto cleanup_and_bail_uncompressed; > + > /* we want to make sure that amount of ram required to uncompress > * an extent is reasonable, so we limit the total size in ram > * of a compressed extent to 128k. This is a crucial number > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
