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Date:   Thu, 3 Oct 2019 21:33:45 +1000
From:   Matthew Bobrowski <mbobrowski@mbobrowski.org>
To:     tytso@mit.edu, jack@suse.cz, adilger.kernel@dilger.ca
Cc:     linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        hch@infradead.org, david@fromorbit.com, darrick.wong@oracle.com
Subject: [PATCH v4 3/8] ext4: introduce new callback for IOMAP_REPORT
 operations
Message-ID: <cb2dcb6970da1b53bdf85583f13ba2aaf1684e96.1570100361.git.mbobrowski@mbobrowski.org>
References: <cover.1570100361.git.mbobrowski@mbobrowski.org>
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Sender: linux-ext4-owner@vger.kernel.org
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As part of ext4_iomap_begin() cleanups and port across direct I/O path
to make use of iomap infrastructure, we split IOMAP_REPORT operations
into a separate ->iomap_begin() handler.

Signed-off-by: Matthew Bobrowski <mbobrowski@mbobrowski.org>
---
 fs/ext4/ext4.h  |   1 +
 fs/ext4/file.c  |   6 ++-
 fs/ext4/inode.c | 129 ++++++++++++++++++++++++++++--------------------
 3 files changed, 80 insertions(+), 56 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 03db3e71676c..d0d88f411a44 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -3379,6 +3379,7 @@ static inline void ext4_clear_io_unwritten_flag(ext4_io_end_t *io_end)
 }
 
 extern const struct iomap_ops ext4_iomap_ops;
+extern const struct iomap_ops ext4_iomap_report_ops;
 
 static inline int ext4_buffer_uptodate(struct buffer_head *bh)
 {
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 8d2bbcc2d813..ab75aee3e687 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -494,12 +494,14 @@ loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
 						maxbytes, i_size_read(inode));
 	case SEEK_HOLE:
 		inode_lock_shared(inode);
-		offset = iomap_seek_hole(inode, offset, &ext4_iomap_ops);
+		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_ops);
+		offset = iomap_seek_data(inode, offset,
+					 &ext4_iomap_report_ops);
 		inode_unlock_shared(inode);
 		break;
 	}
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index caeb3dec0dec..1dace576b8bd 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3439,6 +3439,72 @@ static int ext4_set_iomap(struct inode *inode, struct iomap *iomap, u16 type,
 	return 0;
 }
 
+static u16 ext4_iomap_check_delalloc(struct inode *inode,
+				     struct ext4_map_blocks *map)
+{
+	struct extent_status es;
+	ext4_lblk_t end = map->m_lblk + map->m_len - 1;
+
+	ext4_es_find_extent_range(inode, &ext4_es_is_delayed, map->m_lblk,
+				  end, &es);
+
+	/* Entire range is a hole */
+	if (!es.es_len || es.es_lblk > end)
+		return IOMAP_HOLE;
+	if (es.es_lblk <= map->m_lblk) {
+		ext4_lblk_t offset = 0;
+
+		if (es.es_lblk < map->m_lblk)
+			offset = map->m_lblk - es.es_lblk;
+		map->m_lblk = es.es_lblk + offset;
+		map->m_len = es.es_len - offset;
+		return IOMAP_DELALLOC;
+	}
+
+	/* Range starts with a hole */
+	map->m_len = es.es_lblk - map->m_lblk;
+	return IOMAP_HOLE;
+}
+
+static int ext4_iomap_begin_report(struct inode *inode, loff_t offset,
+				   loff_t length, unsigned flags,
+				   struct iomap *iomap)
+{
+	int ret;
+	u16 type = 0;
+	struct ext4_map_blocks map;
+	u8 blkbits = inode->i_blkbits;
+	unsigned long first_block, last_block;
+
+	if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK)
+		return -EINVAL;
+	first_block = offset >> blkbits;
+	last_block = min_t(loff_t, (offset + length - 1) >> blkbits,
+			   EXT4_MAX_LOGICAL_BLOCK);
+
+	if (ext4_has_inline_data(inode)) {
+		ret = ext4_inline_data_iomap(inode, iomap);
+		if (ret != -EAGAIN) {
+			if (ret == 0 && offset >= iomap->length)
+				ret = -ENOENT;
+			return ret;
+		}
+	}
+
+	map.m_lblk = first_block;
+	map.m_len = last_block = first_block + 1;
+	ret = ext4_map_blocks(NULL, inode, &map, 0);
+	if (ret < 0)
+		return ret;
+	if (ret == 0)
+		type = ext4_iomap_check_delalloc(inode, &map);
+	return ext4_set_iomap(inode, iomap, type, first_block, &map);
+}
+
+const struct iomap_ops ext4_iomap_report_ops = {
+	.iomap_begin = ext4_iomap_begin_report,
+};
+
 static int ext4_iomap_alloc(struct inode *inode,
 			    unsigned flags,
 			    unsigned long first_block,
@@ -3498,12 +3564,10 @@ static int ext4_iomap_alloc(struct inode *inode,
 static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 			    unsigned flags, struct iomap *iomap)
 {
-	u16 type = 0;
-	unsigned int blkbits = inode->i_blkbits;
-	unsigned long first_block, last_block;
-	struct ext4_map_blocks map;
-	bool delalloc = false;
 	int ret;
+	struct ext4_map_blocks map;
+	u8 blkbits = inode->i_blkbits;
+	unsigned long first_block, last_block;
 
 	if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK)
 		return -EINVAL;
@@ -3511,64 +3575,21 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 	last_block = min_t(loff_t, (offset + length - 1) >> blkbits,
 			   EXT4_MAX_LOGICAL_BLOCK);
 
-	if (flags & IOMAP_REPORT) {
-		if (ext4_has_inline_data(inode)) {
-			ret = ext4_inline_data_iomap(inode, iomap);
-			if (ret != -EAGAIN) {
-				if (ret == 0 && offset >= iomap->length)
-					ret = -ENOENT;
-				return ret;
-			}
-		}
-	} else {
-		if (WARN_ON_ONCE(ext4_has_inline_data(inode)))
-			return -ERANGE;
-	}
+	if (WARN_ON_ONCE(ext4_has_inline_data(inode)))
+		return -ERANGE;
 
 	map.m_lblk = first_block;
 	map.m_len = last_block - first_block + 1;
 
-	if (flags & IOMAP_REPORT) {
-		ret = ext4_map_blocks(NULL, inode, &map, 0);
-		if (ret < 0)
-			return ret;
-
-		if (ret == 0) {
-			ext4_lblk_t end = map.m_lblk + map.m_len - 1;
-			struct extent_status es;
-
-			ext4_es_find_extent_range(inode, &ext4_es_is_delayed,
-						  map.m_lblk, end, &es);
-
-			if (!es.es_len || es.es_lblk > end) {
-				/* entire range is a hole */
-			} else if (es.es_lblk > map.m_lblk) {
-				/* range starts with a hole */
-				map.m_len = es.es_lblk - map.m_lblk;
-			} else {
-				ext4_lblk_t offs = 0;
-
-				if (es.es_lblk < map.m_lblk)
-					offs = map.m_lblk - es.es_lblk;
-				map.m_lblk = es.es_lblk + offs;
-				map.m_len = es.es_len - offs;
-				delalloc = true;
-			}
-		}
-	} else if (flags & IOMAP_WRITE) {
+	if (flags & IOMAP_WRITE)
 		ret = ext4_iomap_alloc(inode, flags, first_block, &map);
-	} else {
+	else
 		ret = ext4_map_blocks(NULL, inode, &map, 0);
-		if (ret < 0)
-			return ret;
-	}
 
 	if (ret < 0)
 		return ret;
-
-	if (!ret)
-		type = delalloc ? IOMAP_DELALLOC : IOMAP_HOLE;
-	return ext4_set_iomap(inode, iomap, type, first_block, &map);
+	return ext4_set_iomap(inode, iomap, ret ? 0 : IOMAP_HOLE, first_block,
+			      &map);
 }
 
 static int ext4_iomap_end(struct inode *inode, loff_t offset, loff_t length,
-- 
2.20.1