On Wed, Jul 22, 2020 at 03:34:04PM -0700, Eric Biggers wrote: > So, something like this: > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 44bad4bb8831..2816194db46c 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -3437,6 +3437,15 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length, > map.m_len = min_t(loff_t, (offset + length - 1) >> blkbits, > EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1; > > + /* > + * When inline encryption is enabled, sometimes I/O to an encrypted file > + * has to be broken up to guarantee DUN contiguity. Handle this by > + * limiting the length of the mapping returned. > + */ > + if (!(flags & IOMAP_REPORT)) > + map.m_len = fscrypt_limit_io_blocks(inode, map.m_lblk, > + map.m_len); > + > if (flags & IOMAP_WRITE) > ret = ext4_iomap_alloc(inode, &map, flags); > else > > > That also avoids any confusion between pages and blocks, which is nice. Correction: for fiemap, ext4 actually uses ext4_iomap_begin_report() instead of ext4_iomap_begin(). So we don't need to check for !IOMAP_REPORT. Also it could make sense to limit map.m_len after ext4_iomap_alloc() rather than before, so that we don't limit the length of the extent that gets allocated but rather just the length that gets returned to iomap. - Eric
