Re: [PATCH v3 14/21] iomap: Sub-extent zeroing

From: John Garry
Date: Thu May 30 2024 - 06:42:55 EST

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On 01/05/2024 02:07, Dave Chinner wrote:

blk_opf_t bio_opf;
@@ -288,6 +288,11 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
size_t copied = 0;
size_t orig_count;
+ if (iomap->extent_size)
+ zeroing_size = iomap->extent_size;
+ else
+ zeroing_size = i_blocksize(inode);

Oh, the dissonance!

iomap->extent_size isn't an extent size at all.

The size of the extent the iomap returns is iomap->length. This new
variable is the IO specific "block size" that should be assumed by
the dio code to determine if padding should be done.

IOWs, I think we should add an "io_block_size" field to the iomap,
and every filesystem that supports iomap should set it to the
filesystem block size (i_blocksize(inode)). Then the changes to the
iomap code end up just being:

- unsigned int fs_block_size = i_blocksize(inode), pad;
+ unsigned int fs_block_size = iomap->io_block_size, pad;

And the patch that introduces that infrastructure change will also
change all the filesystem implementations to unconditionally set
iomap->io_block_size to i_blocksize().

JFYI, this is how that change looks:

----8<----

Subject: [PATCH] iomap: Allow filesystens set sub-fs block zeroing size

Allow filesystens to set the sub-fs block zero size, as in future we will
want to extend this feature to support zeroing of block sizes of larger
than the inode block size.

Signed-off-by: John Garry <john.g.garry@xxxxxxxxxx>

diff --git a/block/fops.c b/block/fops.c
index 9d6d86ebefb9..020443078630 100644
--- a/block/fops.c
+++ b/block/fops.c
@@ -402,6 +402,7 @@ static int blkdev_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
iomap->addr = iomap->offset;
iomap->length = isize - iomap->offset;
iomap->flags |= IOMAP_F_BUFFER_HEAD; /* noop for !CONFIG_BUFFER_HEAD */
+ iomap->io_block_size = i_blocksize(inode);
return 0;
}

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 753db965f7c0..665811b1578b 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -7740,6 +7740,7 @@ static int btrfs_dio_iomap_begin(struct inode *inode, loff_t start,
iomap->offset = start;
iomap->bdev = fs_info->fs_devices->latest_dev->bdev;
iomap->length = len;
+ iomap->io_block_size = i_blocksize(inode);
free_extent_map(em);

return 0;
diff --git a/fs/erofs/data.c b/fs/erofs/data.c
index 8be60797ea2f..ea9d2f3eadb3 100644
--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -305,6 +305,7 @@ static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
if (flags & IOMAP_DAX)
iomap->addr += mdev.m_dax_part_off;
}
+ iomap->io_block_size = i_blocksize(inode);
return 0;
}

diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
index 9b248ee5fef2..6ee89f6a078c 100644
--- a/fs/erofs/zmap.c
+++ b/fs/erofs/zmap.c
@@ -749,6 +749,7 @@ static int z_erofs_iomap_begin_report(struct inode *inode, loff_t offset,
if (iomap->offset >= inode->i_size)
iomap->length = length + offset - map.m_la;
}
+ iomap->io_block_size = i_blocksize(inode);
iomap->flags = 0;
return 0;
}
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 0caa1650cee8..7a5539a52844 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -862,6 +862,7 @@ static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
iomap->length = (u64)ret << blkbits;
iomap->flags |= IOMAP_F_MERGED;
}
+ iomap->io_block_size = i_blocksize(inode);

if (new)
iomap->flags |= IOMAP_F_NEW;
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index e067f2dd0335..ce3269874fde 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4933,6 +4933,7 @@ static int ext4_iomap_xattr_fiemap(struct inode *inode, struct iomap *iomap)
iomap->length = length;
iomap->type = iomap_type;
iomap->flags = 0;
+ iomap->io_block_size = i_blocksize(inode);
out:
return error;
}
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 4bae9ccf5fe0..3ec82e4d71c4 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3235,6 +3235,7 @@ static void ext4_set_iomap(struct inode *inode, struct iomap *iomap,
iomap->bdev = inode->i_sb->s_bdev;
iomap->offset = (u64) map->m_lblk << blkbits;
iomap->length = (u64) map->m_len << blkbits;
+ iomap->io_block_size = i_blocksize(inode);

if ((map->m_flags & EXT4_MAP_MAPPED) &&
!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index b9b0debc6b3d..6c12641b9a7b 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -4233,6 +4233,7 @@ static int f2fs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
}
iomap->addr = IOMAP_NULL_ADDR;
}
+ iomap->io_block_size = i_blocksize(inode);

if (map.m_flags & F2FS_MAP_NEW)
iomap->flags |= IOMAP_F_NEW;
diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c
index 12ef91d170bb..68ddc74cb31e 100644
--- a/fs/fuse/dax.c
+++ b/fs/fuse/dax.c
@@ -577,6 +577,7 @@ static int fuse_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
iomap->flags = 0;
iomap->bdev = NULL;
iomap->dax_dev = fc->dax->dev;
+ iomap->io_block_size = i_blocksize(inode);

/*
* Both read/write and mmap path can race here. So we need something
diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index 1795c4e8dbf6..8d2de42b1da9 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -927,6 +927,7 @@ static int __gfs2_iomap_get(struct inode *inode, loff_t pos, loff_t length,

out:
iomap->bdev = inode->i_sb->s_bdev;
+ iomap->io_block_size = i_blocksize(inode);
unlock:
up_read(&ip->i_rw_mutex);
return ret;
diff --git a/fs/hpfs/file.c b/fs/hpfs/file.c
index 1bb8d97cd9ae..5d2718faf520 100644
--- a/fs/hpfs/file.c
+++ b/fs/hpfs/file.c
@@ -149,6 +149,7 @@ static int hpfs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
iomap->addr = IOMAP_NULL_ADDR;
iomap->length = 1 << blkbits;
}
+ iomap->io_block_size = i_blocksize(inode);

hpfs_unlock(sb);
return 0;
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index f3b43d223a46..1e6eb59cac6c 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -277,7 +277,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
{
const struct iomap *iomap = &iter->iomap;
struct inode *inode = iter->inode;
- unsigned int fs_block_size = i_blocksize(inode), pad;
+ u64 io_block_size = iomap->io_block_size;
loff_t length = iomap_length(iter);
loff_t pos = iter->pos;
blk_opf_t bio_opf;
@@ -287,6 +287,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
int nr_pages, ret = 0;
size_t copied = 0;
size_t orig_count;
+ unsigned int pad;

if ((pos | length) & (bdev_logical_block_size(iomap->bdev) - 1) ||
!bdev_iter_is_aligned(iomap->bdev, dio->submit.iter))
@@ -355,7 +356,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,

if (need_zeroout) {
/* zero out from the start of the block to the write offset */
- pad = pos & (fs_block_size - 1);
+ pad = pos & (io_block_size - 1);
if (pad)
iomap_dio_zero(iter, dio, pos - pad, pad);
}
@@ -429,9 +430,9 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
if (need_zeroout ||
((dio->flags & IOMAP_DIO_WRITE) && pos >= i_size_read(inode))) {
/* zero out from the end of the write to the end of the block */
- pad = pos & (fs_block_size - 1);
+ pad = pos & (io_block_size - 1);
if (pad)
- iomap_dio_zero(iter, dio, pos, fs_block_size - pad);
+ iomap_dio_zero(iter, dio, pos, io_block_size - pad);
}
out:
/* Undo iter limitation to current extent */
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 378342673925..ecb4cae88248 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -127,6 +127,7 @@ xfs_bmbt_to_iomap(
}
iomap->offset = XFS_FSB_TO_B(mp, imap->br_startoff);
iomap->length = XFS_FSB_TO_B(mp, imap->br_blockcount);
+ iomap->io_block_size = i_blocksize(VFS_I(ip));
if (mapping_flags & IOMAP_DAX)
iomap->dax_dev = target->bt_daxdev;
else
diff --git a/fs/zonefs/file.c b/fs/zonefs/file.c
index 3b103715acc9..bf2cc4bee309 100644
--- a/fs/zonefs/file.c
+++ b/fs/zonefs/file.c
@@ -50,6 +50,7 @@ static int zonefs_read_iomap_begin(struct inode *inode, loff_t offset,
iomap->addr = (z->z_sector << SECTOR_SHIFT) + iomap->offset;
iomap->length = isize - iomap->offset;
}
+ iomap->io_block_size = i_blocksize(inode);
mutex_unlock(&zi->i_truncate_mutex);

trace_zonefs_iomap_begin(inode, iomap);
@@ -99,6 +100,7 @@ static int zonefs_write_iomap_begin(struct inode *inode, loff_t offset,
iomap->type = IOMAP_MAPPED;
iomap->length = isize - iomap->offset;
}
+ iomap->io_block_size = i_blocksize(inode);
mutex_unlock(&zi->i_truncate_mutex);

trace_zonefs_iomap_begin(inode, iomap);
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 6fc1c858013d..c6ae6fdcec00 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -103,6 +103,7 @@ struct iomap {
void *private; /* filesystem private */
const struct iomap_folio_ops *folio_ops;
u64 validity_cookie; /* used with .iomap_valid() */
+ u64 io_block_size; /* sub-FS block zeroing size */
};

static inline sector_t iomap_sector(const struct iomap *iomap, loff_t pos)

---->8----

That's a lot changes... in addition, if rtextsize is to be considered in setting io_block_size, what about ext4 bigalloc and other similar features?

Then, in a separate patch, you can add XFS support for large IO
block sizes when we have either a large rtextsize or extent size
hints set.

+
if ((pos | length) & (bdev_logical_block_size(iomap->bdev) - 1) ||
!bdev_iter_is_aligned(iomap->bdev, dio->submit.iter))

Next message: Thierry Reding: "Re: [PATCH v2 02/20] pinctrl: tegra: Use scope based of_node_put() cleanups"
Previous message: Huacai Chen: "Re: [PATCH v3 3/4] LoongArch: Fix entry point in image header"
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