On Fri, Sep 27, 2024 at 02:53:44PM +0800, Julian Sun wrote: > Attempting to unshare extents beyond EOF will trigger > the need zeroing case, which in turn triggers a warning. > Therefore, let's skip the unshare process if blocks are > beyond EOF. > > This patch passed the xfstests using './check -g quick', without > causing any additional failure > > Reported-and-tested-by: syzbot+296b1c84b9cbf306e5a0@xxxxxxxxxxxxxxxxxxxxxxxxx > Closes: https://syzkaller.appspot.com/bug?extid=296b1c84b9cbf306e5a0 > Fixes: 32a38a499104 ("iomap: use write_begin to read pages to unshare") > Inspired-by: Dave Chinner <david@xxxxxxxxxxxxx> > Signed-off-by: Julian Sun <sunjunchao2870@xxxxxxxxx> > --- > fs/xfs/xfs_iomap.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c > index 72c981e3dc92..81a0514b8652 100644 > --- a/fs/xfs/xfs_iomap.c > +++ b/fs/xfs/xfs_iomap.c > @@ -976,6 +976,7 @@ xfs_buffered_write_iomap_begin( > int error = 0; > unsigned int lockmode = XFS_ILOCK_EXCL; > u64 seq; > + xfs_fileoff_t eof_fsb; > > if (xfs_is_shutdown(mp)) > return -EIO; > @@ -1016,6 +1017,13 @@ xfs_buffered_write_iomap_begin( > if (eof) > imap.br_startoff = end_fsb; /* fake hole until the end */ > > + /* Don't try to unshare any blocks beyond EOF. */ > + eof_fsb = XFS_B_TO_FSB(mp, XFS_ISIZE(ip)); > + if (flags & IOMAP_UNSHARE && end_fsb > eof_fsb) { > + xfs_trim_extent(&imap, offset_fsb, eof_fsb - offset_fsb); > + end_fsb = eof_fsb; > + } No. The EOF check/limiting needs to be at a higher level - probably in xfs_falloc_unshare_range() because the existing xfs_falloc_newsize() call implements the wrong file size growing semantics for UNSHARE... -Dave. -- Dave Chinner david@xxxxxxxxxxxxx
