On Fri, Jun 13, 2025 at 11:42:17AM +0200, Jan Kara wrote: > On Fri 13-06-25 11:18:38, Wei Gao wrote: > > Previously, ext2_fiemap would unconditionally apply "len = min_t(u64, len, > > i_size_read(inode));", When inode->i_size was 0 (for an empty file), this > > would reduce the requested len to 0. Passing len = 0 to iomap_fiemap could > > then result in an -EINVAL error, even for valid queries on empty files. > > > > Link: https://github.com/linux-test-project/ltp/issues/1246 > > Signed-off-by: Wei Gao <wegao@xxxxxxxx> > > ... > > > diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c > > index 30f8201c155f..591db2b4390a 100644 > > --- a/fs/ext2/inode.c > > +++ b/fs/ext2/inode.c > > @@ -895,9 +895,15 @@ int ext2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, > > u64 start, u64 len) > > { > > int ret; > > + u64 i_size; > > > > inode_lock(inode); > > - len = min_t(u64, len, i_size_read(inode)); > > + > > + i_size = i_size_read(inode); > > + > > + if (i_size > 0) > > + len = min_t(u64, len, i_size_read(inode)); > > > Thanks! This would actually lead to excessively slow fiemap for 0-length > files. So what I've ended up with is attached modification of your patch. Thank you for your patient review, I really appreciate it. BTW i have stupid question: Where can I see the real-time status of this patch? such as whether it has been merged? I have checked https://patchwork.kernel.org/project/linux-fsdevel/list/ but do not find current patch, maybe this patch need specific sent it to linux-fsdevel@xxxxxxxxxxxxxxx? I just get maillist through scripts/get_maintainer.pl but mail list not contain linux-fsdevel@xxxxxxxxxxxxxxx. > > > + > > ret = iomap_fiemap(inode, fieinfo, start, len, &ext2_iomap_ops); > > inode_unlock(inode); > > > > -- > > 2.49.0 > > > -- > Jan Kara <jack@xxxxxxxx> > SUSE Labs, CR > --- > > From a099b09a3342a0b28ea330e405501b5b4d0424b4 Mon Sep 17 00:00:00 2001 > From: Wei Gao <wegao@xxxxxxxx> > Date: Fri, 13 Jun 2025 11:18:38 -0400 > Subject: [PATCH] ext2: Handle fiemap on empty files to prevent EINVAL > > Previously, ext2_fiemap would unconditionally apply "len = min_t(u64, len, > i_size_read(inode));", When inode->i_size was 0 (for an empty file), this > would reduce the requested len to 0. Passing len = 0 to iomap_fiemap could > then result in an -EINVAL error, even for valid queries on empty files. > > Link: https://github.com/linux-test-project/ltp/issues/1246 > Signed-off-by: Wei Gao <wegao@xxxxxxxx> > Signed-off-by: Jan Kara <jack@xxxxxxx> > Link: https://patch.msgid.link/20250613152402.3432135-1-wegao@xxxxxxxx > --- > fs/ext2/inode.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c > index 30f8201c155f..177b1f852b63 100644 > --- a/fs/ext2/inode.c > +++ b/fs/ext2/inode.c > @@ -895,9 +895,19 @@ int ext2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, > u64 start, u64 len) > { > int ret; > + loff_t i_size; > > inode_lock(inode); > - len = min_t(u64, len, i_size_read(inode)); > + i_size = i_size_read(inode); > + /* > + * iomap_fiemap() returns EINVAL for 0 length. Make sure we don't trim > + * length to 0 but still trim the range as much as possible since > + * ext2_get_blocks() iterates unmapped space block by block which is > + * slow. > + */ > + if (i_size == 0) > + i_size = 1; > + len = min_t(u64, len, i_size); > ret = iomap_fiemap(inode, fieinfo, start, len, &ext2_iomap_ops); > inode_unlock(inode); > > -- > 2.43.0 >
