diff mbox series

[1/7] iomap: merge iomap_seek_hole() and iomap_seek_data()

Message ID 20230726102603.155522-2-hao.xu@linux.dev (mailing list archive)
State New
Headers show
Series io_uring lseek | expand

Commit Message

Hao Xu July 26, 2023, 10:25 a.m. UTC 
From: Hao Xu <howeyxu@tencent.com>

The two functions share almost same code, merge them together.
No functional change in this patch.

Signed-off-by: Hao Xu <howeyxu@tencent.com>
---
 fs/ext4/file.c        |  9 ++-------
 fs/gfs2/inode.c       |  4 ++--
 fs/iomap/seek.c       | 40 ++++++++--------------------------------
 fs/xfs/xfs_file.c     |  5 ++---
 include/linux/iomap.h |  6 ++----
 5 files changed, 16 insertions(+), 48 deletions(-)

Comments

Dave Chinner July 26, 2023, 9:50 p.m. UTC | #1 
On Wed, Jul 26, 2023 at 06:25:57PM +0800, Hao Xu wrote:
> From: Hao Xu <howeyxu@tencent.com>
> 
> The two functions share almost same code, merge them together.
> No functional change in this patch.

No, please don't. seek data and seek hole have subtly different
semantics and return values, and we've explicitly kept them separate
because it's much easier to maintain them as separate functions with
separate semantics than combine them into a single function with
lots of non-obvious conditional behaviour.

The fact that the new iomap_seek() API requires a boolean "SEEK_DATA
or SEEK_HOLE" field to indicate that the caller wants makes it clear
that this isn't actually an improvement over explicit
iomap_seek_data() and iomap_seek_hole() API calls.

-Dave.
Hao Xu July 27, 2023, 12:10 p.m. UTC | #2 
On 7/27/23 05:50, Dave Chinner wrote:
> On Wed, Jul 26, 2023 at 06:25:57PM +0800, Hao Xu wrote:
>> From: Hao Xu <howeyxu@tencent.com>
>>
>> The two functions share almost same code, merge them together.
>> No functional change in this patch.
> 
> No, please don't. seek data and seek hole have subtly different
> semantics and return values, and we've explicitly kept them separate
> because it's much easier to maintain them as separate functions with
> separate semantics than combine them into a single function with
> lots of non-obvious conditional behaviour.
> 
> The fact that the new iomap_seek() API requires a boolean "SEEK_DATA
> or SEEK_HOLE" field to indicate that the caller wants makes it clear
> that this isn't actually an improvement over explicit
> iomap_seek_data() and iomap_seek_hole() API calls.
> 
> -Dave.

I'll revert it back in next version. Thanks.
diff mbox series

Patch

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index c457c8517f0f..3d59993bce56 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -936,15 +936,10 @@  loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
 		return generic_file_llseek_size(file, offset, whence,
 						maxbytes, i_size_read(inode));
 	case SEEK_HOLE:
-		inode_lock_shared(inode);
-		offset = iomap_seek_hole(inode, offset,
-					 &ext4_iomap_report_ops);
-		inode_unlock_shared(inode);
-		break;
 	case SEEK_DATA:
 		inode_lock_shared(inode);
-		offset = iomap_seek_data(inode, offset,
-					 &ext4_iomap_report_ops);
+		offset = iomap_seek(inode, offset, &ext4_iomap_report_ops,
+				    whence == SEEK_HOLE);
 		inode_unlock_shared(inode);
 		break;
 	}
diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index 17c994a0c0d0..628f9d014491 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -2111,7 +2111,7 @@  loff_t gfs2_seek_data(struct file *file, loff_t offset)
 	inode_lock_shared(inode);
 	ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
 	if (!ret)
-		ret = iomap_seek_data(inode, offset, &gfs2_iomap_ops);
+		ret = iomap_seek(inode, offset, &gfs2_iomap_ops, false);
 	gfs2_glock_dq_uninit(&gh);
 	inode_unlock_shared(inode);
 
@@ -2130,7 +2130,7 @@  loff_t gfs2_seek_hole(struct file *file, loff_t offset)
 	inode_lock_shared(inode);
 	ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
 	if (!ret)
-		ret = iomap_seek_hole(inode, offset, &gfs2_iomap_ops);
+		ret = iomap_seek(inode, offset, &gfs2_iomap_ops, true);
 	gfs2_glock_dq_uninit(&gh);
 	inode_unlock_shared(inode);
 
diff --git a/fs/iomap/seek.c b/fs/iomap/seek.c
index a845c012b50c..5e8641c5f0da 100644
--- a/fs/iomap/seek.c
+++ b/fs/iomap/seek.c
@@ -30,32 +30,6 @@  static loff_t iomap_seek_hole_iter(const struct iomap_iter *iter,
 	}
 }
 
-loff_t
-iomap_seek_hole(struct inode *inode, loff_t pos, const struct iomap_ops *ops)
-{
-	loff_t size = i_size_read(inode);
-	struct iomap_iter iter = {
-		.inode	= inode,
-		.pos	= pos,
-		.flags	= IOMAP_REPORT,
-	};
-	int ret;
-
-	/* Nothing to be found before or beyond the end of the file. */
-	if (pos < 0 || pos >= size)
-		return -ENXIO;
-
-	iter.len = size - pos;
-	while ((ret = iomap_iter(&iter, ops)) > 0)
-		iter.processed = iomap_seek_hole_iter(&iter, &pos);
-	if (ret < 0)
-		return ret;
-	if (iter.len) /* found hole before EOF */
-		return pos;
-	return size;
-}
-EXPORT_SYMBOL_GPL(iomap_seek_hole);
-
 static loff_t iomap_seek_data_iter(const struct iomap_iter *iter,
 		loff_t *hole_pos)
 {
@@ -77,7 +51,8 @@  static loff_t iomap_seek_data_iter(const struct iomap_iter *iter,
 }
 
 loff_t
-iomap_seek_data(struct inode *inode, loff_t pos, const struct iomap_ops *ops)
+iomap_seek(struct inode *inode, loff_t pos, const struct iomap_ops *ops,
+	   bool hole)
 {
 	loff_t size = i_size_read(inode);
 	struct iomap_iter iter = {
@@ -93,12 +68,13 @@  iomap_seek_data(struct inode *inode, loff_t pos, const struct iomap_ops *ops)
 
 	iter.len = size - pos;
 	while ((ret = iomap_iter(&iter, ops)) > 0)
-		iter.processed = iomap_seek_data_iter(&iter, &pos);
+		iter.processed = hole ? iomap_seek_hole_iter(&iter, &pos) :
+				 iomap_seek_data_iter(&iter, &pos);
 	if (ret < 0)
 		return ret;
-	if (iter.len) /* found data before EOF */
+	if (iter.len) /* found hole/data before EOF */
 		return pos;
-	/* We've reached the end of the file without finding data */
-	return -ENXIO;
+	/* We've reached the end of the file without finding hole/data */
+	return hole ? size : -ENXIO;
 }
-EXPORT_SYMBOL_GPL(iomap_seek_data);
+EXPORT_SYMBOL_GPL(iomap_seek);
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 4f502219ae4f..d7d37f8fb6bc 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1271,10 +1271,9 @@  xfs_file_llseek(
 	default:
 		return generic_file_llseek(file, offset, whence);
 	case SEEK_HOLE:
-		offset = iomap_seek_hole(inode, offset, &xfs_seek_iomap_ops);
-		break;
 	case SEEK_DATA:
-		offset = iomap_seek_data(inode, offset, &xfs_seek_iomap_ops);
+		offset = iomap_seek(inode, offset, &xfs_seek_iomap_ops,
+				    whence == SEEK_HOLE);
 		break;
 	}
 
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index e2b836c2e119..22d5f9b19a22 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -274,10 +274,8 @@  vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf,
 			const struct iomap_ops *ops);
 int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		u64 start, u64 len, const struct iomap_ops *ops);
-loff_t iomap_seek_hole(struct inode *inode, loff_t offset,
-		const struct iomap_ops *ops);
-loff_t iomap_seek_data(struct inode *inode, loff_t offset,
-		const struct iomap_ops *ops);
+loff_t iomap_seek(struct inode *inode, loff_t offset,
+		  const struct iomap_ops *ops, bool hole);
 sector_t iomap_bmap(struct address_space *mapping, sector_t bno,
 		const struct iomap_ops *ops);