On Wed, Oct 16, 2019 at 04:11:01PM +1100, Dave Chinner wrote: > From: Dave Chinner <dchinner@xxxxxxxxxx> > > When doing a direct IO that spans the current EOF, and there are > written blocks beyond EOF that extend beyond the current write, the > only metadata update that needs to be done is a file size extension. > > However, we don't mark such iomaps as IOMAP_F_DIRTY to indicate that > there is IO completion metadata updates required, and hence we may > fail to correctly sync file size extensions made in IO completion > when O_DSYNC writes are beingt used and the hardware supports FUA. > > Hence when setting IOMAP_F_DIRTY, we need to also take into account > whether the iomap spans the current EOF. If it does, then we need to > mark it dirty so that IO completion will call generic_write_sync() > to flush the inode size update to stable storage correctly. > > Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx> > --- > fs/ext4/inode.c | 9 ++++++++- > fs/xfs/xfs_iomap.c | 8 ++++++++ > include/linux/iomap.h | 2 ++ > 3 files changed, 18 insertions(+), 1 deletion(-) > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 516faa280ced..e9dc52537e5b 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -3523,9 +3523,16 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length, > return ret; > } > > + /* > + * Writes that span EOF might trigger an IO size update on completion, > + * so consider them to be dirty for the purposes of O_DSYNC even if > + * there is no other metadata changes being made or are pending here. > + */ > iomap->flags = 0; > - if (ext4_inode_datasync_dirty(inode)) > + if (ext4_inode_datasync_dirty(inode) || > + offset + length > i_size_read(inode)) > iomap->flags |= IOMAP_F_DIRTY; > + > iomap->bdev = inode->i_sb->s_bdev; > iomap->dax_dev = sbi->s_daxdev; > iomap->offset = (u64)first_block << blkbits; > diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c > index f780e223b118..38be06f19ea2 100644 > --- a/fs/xfs/xfs_iomap.c > +++ b/fs/xfs/xfs_iomap.c > @@ -722,6 +722,14 @@ xfs_file_iomap_begin_delay( > xfs_trim_extent(&imap, cmap.br_startoff, cmap.br_blockcount); > shared = true; > } > + > + /* > + * Writes that span EOF might trigger an IO size update on completion, > + * so consider them to be dirty for the purposes of O_DSYNC even if > + * there is no other metadata changes being made or are pending here. > + */ > + if (offset + count > i_size_read(inode)) > + iomap->flags |= IOMAP_F_DIRTY; > error = xfs_bmbt_to_iomap(ip, iomap, &imap, shared); > out_unlock: > xfs_iunlock(ip, XFS_ILOCK_EXCL); Urk, self-nack. I put this in the wrong function. Too much spaghetti that all looks similar in the XFS iomap code now. Will repost in a minute. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx
