Re: [PATCH 1/4] iomap: Switch from blkno to disk offset

Darrick J. Wong
2017-08-31T21:32:35Z

On Tue, Aug 29, 2017 at 09:11:15AM -0700, Darrick J. Wong wrote:
> On Tue, Aug 29, 2017 at 04:29:39PM +0200, Andreas Gruenbacher wrote:
> > Replace iomap->blkno, the sector number, with iomap->addr, the disk
> > offset in bytes. For invalid disk offsets, use the special value
> > IOMAP_NULL_ADDR instead of IOMAP_NULL_BLOCK. This allows to use iomap
> > for mappings which are not block aligned, such as inline data on ext4
> > and stuffed inodes on gfs2.
> >
> > Tested on xfs and ext4 with xfstests; seems to be working correctly.
> >
> > Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
> > ---
> > fs/buffer.c | 4 ++--
> > fs/dax.c | 2 +-
> > fs/ext2/inode.c | 4 ++--
> > fs/ext4/inode.c | 4 ++--
> > fs/iomap.c | 11 +++++------
> > fs/nfsd/blocklayout.c | 4 ++--
> > fs/xfs/xfs_iomap.c | 6 +++---
> > include/linux/iomap.h | 10 +++++-----
> > 8 files changed, 22 insertions(+), 23 deletions(-)
> >
> > diff --git a/fs/buffer.c b/fs/buffer.c
> > index 5715dac7821f..b9d20076bb8f 100644
> > --- a/fs/buffer.c
> > +++ b/fs/buffer.c
> > @@ -1979,8 +1979,8 @@ iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh,
> > case IOMAP_MAPPED:
> > if (offset >= i_size_read(inode))
> > set_buffer_new(bh);
> > - bh->b_blocknr = (iomap->blkno >> (inode->i_blkbits - 9)) +
> > - ((offset - iomap->offset) >> inode->i_blkbits);
> > + bh->b_blocknr = (iomap->addr + offset - iomap->offset) >>
> > + inode->i_blkbits;
> > set_buffer_mapped(bh);
> > break;
> > }
> > diff --git a/fs/dax.c b/fs/dax.c
> > index 865d42c63e23..539aaa0b9c45 100644
> > --- a/fs/dax.c
> > +++ b/fs/dax.c
> > @@ -987,7 +987,7 @@ EXPORT_SYMBOL_GPL(__dax_zero_page_range);
> >
> > static sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos)
> > {
> > - return iomap->blkno + (((pos & PAGE_MASK) - iomap->offset) >> 9);
> > + return (iomap->addr + (pos & PAGE_MASK) - iomap->offset) >> 9;
> > }
> >
> > static loff_t
> > diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
> > index 30163d007b2f..e7d8925d0140 100644
> > --- a/fs/ext2/inode.c
> > +++ b/fs/ext2/inode.c
> > @@ -824,11 +824,11 @@ static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> >
> > if (ret == 0) {
> > iomap->type = IOMAP_HOLE;
> > - iomap->blkno = IOMAP_NULL_BLOCK;
> > + iomap->addr = IOMAP_NULL_ADDR;
> > iomap->length = 1 << blkbits;
> > } else {
> > iomap->type = IOMAP_MAPPED;
> > - iomap->blkno = (sector_t)bno << (blkbits - 9);
> > + iomap->addr = (u64)bno << blkbits;
> > iomap->length = (u64)ret << blkbits;
> > iomap->flags |= IOMAP_F_MERGED;
> > }
> > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> > index c774bdc22759..429f0afde9f2 100644
> > --- a/fs/ext4/inode.c
> > +++ b/fs/ext4/inode.c
> > @@ -3483,7 +3483,7 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> >
> > if (ret == 0) {
> > iomap->type = IOMAP_HOLE;
> > - iomap->blkno = IOMAP_NULL_BLOCK;
> > + iomap->addr = IOMAP_NULL_ADDR;
> > iomap->length = (u64)map.m_len << blkbits;
> > } else {
> > if (map.m_flags & EXT4_MAP_MAPPED) {
> > @@ -3494,7 +3494,7 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> > WARN_ON_ONCE(1);
> > return -EIO;
> > }
> > - iomap->blkno = (sector_t)map.m_pblk << (blkbits - 9);
> > + iomap->addr = (u64)map.m_pblk << blkbits;
> > iomap->length = (u64)map.m_len << blkbits;
> > }
> >
> > diff --git a/fs/iomap.c b/fs/iomap.c
> > index 59cc98ad7577..7bc1797c2292 100644
> > --- a/fs/iomap.c
> > +++ b/fs/iomap.c
> > @@ -350,8 +350,8 @@ static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset,
> > static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes,
> > struct iomap *iomap)
> > {
> > - sector_t sector = iomap->blkno +
> > - (((pos & ~(PAGE_SIZE - 1)) - iomap->offset) >> 9);
> > + sector_t sector = (iomap->addr +
> > + (pos & PAGE_MASK) - iomap->offset) >> 9;
> >
> > return __dax_zero_page_range(iomap->bdev, iomap->dax_dev, sector,
> > offset, bytes);
> > @@ -512,9 +512,8 @@ static int iomap_to_fiemap(struct fiemap_extent_info *fi,
> > flags |= FIEMAP_EXTENT_SHARED;
> >
> > return fiemap_fill_next_extent(fi, iomap->offset,
> > - iomap->blkno != IOMAP_NULL_BLOCK ? iomap->blkno << 9: 0,
> > + iomap->addr != IOMAP_NULL_ADDR ? iomap->addr : 0,
> > iomap->length, flags);
> > -
> > }
> >
> > static loff_t
> > @@ -807,7 +806,7 @@ iomap_dio_zero(struct iomap_dio *dio, struct iomap *iomap, loff_t pos,
> > bio = bio_alloc(GFP_KERNEL, 1);
> > bio->bi_bdev = iomap->bdev;
> > bio->bi_iter.bi_sector =
> > - iomap->blkno + ((pos - iomap->offset) >> 9);
> > + (iomap->addr + pos - iomap->offset) >> 9;
> > bio->bi_private = dio;
> > bio->bi_end_io = iomap_dio_bio_end_io;
> >
> > @@ -886,7 +885,7 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
> > bio = bio_alloc(GFP_KERNEL, nr_pages);
> > bio->bi_bdev = iomap->bdev;
> > bio->bi_iter.bi_sector =
> > - iomap->blkno + ((pos - iomap->offset) >> 9);
> > + (iomap->addr + pos - iomap->offset) >> 9;
> > bio->bi_write_hint = dio->iocb->ki_hint;
> > bio->bi_private = dio;
> > bio->bi_end_io = iomap_dio_bio_end_io;
> > diff --git a/fs/nfsd/blocklayout.c b/fs/nfsd/blocklayout.c
> > index c862c2489df0..2d1d37b27dc7 100644
> > --- a/fs/nfsd/blocklayout.c
> > +++ b/fs/nfsd/blocklayout.c
> > @@ -65,7 +65,7 @@ nfsd4_block_proc_layoutget(struct inode *inode, const struct svc_fh *fhp,
> > bex->es = PNFS_BLOCK_READ_DATA;
> > else
> > bex->es = PNFS_BLOCK_READWRITE_DATA;
> > - bex->soff = (iomap.blkno << 9);
> > + bex->soff = iomap.addr;
> > break;
> > case IOMAP_UNWRITTEN:
> > if (seg->iomode & IOMODE_RW) {
> > @@ -78,7 +78,7 @@ nfsd4_block_proc_layoutget(struct inode *inode, const struct svc_fh *fhp,
> > }
> >
> > bex->es = PNFS_BLOCK_INVALID_DATA;
> > - bex->soff = (iomap.blkno << 9);
> > + bex->soff = iomap.addr;
> > break;
> > }
> > /*FALLTHRU*/
> > diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> > index 813394c62849..1bcc5d0373a5 100644
> > --- a/fs/xfs/xfs_iomap.c
> > +++ b/fs/xfs/xfs_iomap.c
> > @@ -54,13 +54,13 @@ xfs_bmbt_to_iomap(
> > struct xfs_mount *mp = ip->i_mount;
> >
> > if (imap->br_startblock == HOLESTARTBLOCK) {
> > - iomap->blkno = IOMAP_NULL_BLOCK;
> > + iomap->addr = IOMAP_NULL_ADDR;
> > iomap->type = IOMAP_HOLE;
> > } else if (imap->br_startblock == DELAYSTARTBLOCK) {
> > - iomap->blkno = IOMAP_NULL_BLOCK;
> > + iomap->addr = IOMAP_NULL_ADDR;
> > iomap->type = IOMAP_DELALLOC;
> > } else {
> > - iomap->blkno = xfs_fsb_to_db(ip, imap->br_startblock);
> > + iomap->addr = (u64)xfs_fsb_to_db(ip, imap->br_startblock) << 9;
>
> iomap->addr = BBTOB(xfs_fsb_to_db(...));
>
> Same machine-level transformation, but please help us maintain
> consistent unit conversion code; the 'BBTOB' name makes the units
> analysis of a given piece of code more straightforward.
>
> With that fixed,
> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
>
> for the iomap and XFS parts.

FWIW I still want the BBTOB thing fixed in whatever patch lands
upstream, but I tested the first two patches in this series and nothing
blew up so I guess everything works ok.

--D

>
> --D
>
> > if (imap->br_state == XFS_EXT_UNWRITTEN)
> > iomap->type = IOMAP_UNWRITTEN;
> > else
> > diff --git a/include/linux/iomap.h b/include/linux/iomap.h
> > index f64dc6ce5161..7b8a615fa021 100644
> > --- a/include/linux/iomap.h
> > +++ b/include/linux/iomap.h
> > @@ -15,8 +15,8 @@ struct vm_fault;
> > */
> > #define IOMAP_HOLE 0x01 /* no blocks allocated, need allocation */
> > #define IOMAP_DELALLOC 0x02 /* delayed allocation blocks */
> > -#define IOMAP_MAPPED 0x03 /* blocks allocated @blkno */
> > -#define IOMAP_UNWRITTEN 0x04 /* blocks allocated @blkno in unwritten state */
> > +#define IOMAP_MAPPED 0x03 /* blocks allocated at @addr */
> > +#define IOMAP_UNWRITTEN 0x04 /* blocks allocated at @addr in unwritten state */
> >
> > /*
> > * Flags for all iomap mappings:
> > @@ -30,12 +30,12 @@ struct vm_fault;
> > #define IOMAP_F_SHARED 0x20 /* block shared with another file */
> >
> > /*
> > - * Magic value for blkno:
> > + * Magic value for addr:
> > */
> > -#define IOMAP_NULL_BLOCK -1LL /* blkno is not valid */
> > +#define IOMAP_NULL_ADDR -1ULL /* addr is not valid */
> >
> > struct iomap {
> > - sector_t blkno; /* 1st sector of mapping, 512b units */
> > + u64 addr; /* disk offset of mapping, bytes */
> > loff_t offset; /* file offset of mapping, bytes */
> > u64 length; /* length of mapping, bytes */
> > u16 type; /* type of mapping */
> > --
> > 2.13.3
> >
> > --
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