[PATCH v2 0/4] ext4: SEEK_HOLE / SEEK_DATA via iomap

[PATCH v2 0/4] ext4: SEEK_HOLE / SEEK_DATA via iomap

[Andreas Gruenbacher]

Add IOMAP_REPORT support to ext4, including support for inline data
which iomap couldn't report so far.  Switch to iomap_seek_{hole,data} on
ext4.

This patch series should be ready to be merged.

Andreas Gruenbacher (3):
  iomap: Switch from blkno to disk offset
  iomap: Add IOMAP_F_DATA_INLINE flag
  ext4: Add iomap support for inline data

Christoph Hellwig (1):
  ext4: Switch to iomap for SEEK_HOLE / SEEK_DATA

 fs/buffer.c           |   4 +-
 fs/dax.c              |   2 +-
 fs/ext2/inode.c       |   4 +-
 fs/ext4/Kconfig       |   1 +
 fs/ext4/ext4.h        |   7 +-
 fs/ext4/file.c        | 263 +++-----------------------------------------------
 fs/ext4/inline.c      |  33 +++++++
 fs/ext4/inode.c       | 149 +++++++++++++---------------
 fs/iomap.c            |  13 +--
 fs/nfsd/blocklayout.c |   4 +-
 fs/xfs/xfs_iomap.c    |   6 +-
 include/linux/iomap.h |  15 +--
 12 files changed, 142 insertions(+), 359 deletions(-)

-- 
2.13.3

[PATCH v2 1/4] iomap: Switch from blkno to disk offset

[Andreas Gruenbacher]

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.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>  # iomap, xfs
Reviewed-by: Jan Kara <jack@suse.cz>
---
 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 170df856bdb9..bd4d0923cdce 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1978,8 +1978,8 @@ 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 6afcacb3a87b..feccb4ec45d2 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -938,7 +938,7 @@ 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 4dca6f348714..1b8fc73de4a1 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -820,11 +820,11 @@ 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 31db875bc7a1..d9e633c12aae 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3472,7 +3472,7 @@ 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) {
@@ -3483,7 +3483,7 @@ 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 269b24a01f32..622c731c57a0 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_set_dev(bio, 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_set_dev(bio, 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 a1909bc064e9..ac22a5c00079 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 = BBTOB(xfs_fsb_to_db(ip, imap->br_startblock));
 		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

[PATCH v2 2/4] iomap: Add IOMAP_F_DATA_INLINE flag

[Andreas Gruenbacher]

Add a new IOMAP_F_DATA_INLINE flag to indicate that a mapping is in a
disk area that contains data as well as metadata.  In iomap_fiemap, map
this flag to FIEMAP_EXTENT_DATA_INLINE.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
---
 fs/iomap.c            | 2 ++
 include/linux/iomap.h | 5 +++--
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/iomap.c b/fs/iomap.c
index 622c731c57a0..20b303ac109b 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -510,6 +510,8 @@ static int iomap_to_fiemap(struct fiemap_extent_info *fi,
 		flags |= FIEMAP_EXTENT_MERGED;
 	if (iomap->flags & IOMAP_F_SHARED)
 		flags |= FIEMAP_EXTENT_SHARED;
+	if (iomap->flags & IOMAP_F_DATA_INLINE)
+		flags |= FIEMAP_EXTENT_DATA_INLINE;
 
 	return fiemap_fill_next_extent(fi, iomap->offset,
 			iomap->addr != IOMAP_NULL_ADDR ? iomap->addr : 0,
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 7b8a615fa021..2b0790dbd6ea 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -26,8 +26,9 @@ struct vm_fault;
 /*
  * Flags that only need to be reported for IOMAP_REPORT requests:
  */
-#define IOMAP_F_MERGED	0x10	/* contains multiple blocks/extents */
-#define IOMAP_F_SHARED	0x20	/* block shared with another file */
+#define IOMAP_F_MERGED		0x10	/* contains multiple blocks/extents */
+#define IOMAP_F_SHARED		0x20	/* block shared with another file */
+#define IOMAP_F_DATA_INLINE	0x40	/* data inline in the inode */
 
 /*
  * Magic value for addr:
-- 
2.13.3

[PATCH v2 3/4] ext4: Add iomap support for inline data

[Andreas Gruenbacher]

Report inline data as a IOMAP_F_DATA_INLINE mapping.  This allows to use
iomap_seek_hole and iomap_seek_data in ext4_llseek and makes switching
to iomap_fiemap in ext4_fiemap easier.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/ext4.h   |  4 ++++
 fs/ext4/inline.c | 33 +++++++++++++++++++++++++++++++++
 fs/ext4/inode.c  | 16 ++++++++++++++--
 3 files changed, 51 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index e2abe01c8c6b..ae3e4a25821a 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -3048,6 +3048,10 @@ extern struct buffer_head *ext4_get_first_inline_block(struct inode *inode,
 extern int ext4_inline_data_fiemap(struct inode *inode,
 				   struct fiemap_extent_info *fieinfo,
 				   int *has_inline, __u64 start, __u64 len);
+
+struct iomap;
+extern int ext4_inline_data_iomap(struct inode *inode, struct iomap *iomap);
+
 extern int ext4_try_to_evict_inline_data(handle_t *handle,
 					 struct inode *inode,
 					 int needed);
diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index 28c5c3abddb3..f0bbc8cb6555 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -12,6 +12,7 @@
  * GNU General Public License for more details.
  */
 
+#include <linux/iomap.h>
 #include <linux/fiemap.h>
 
 #include "ext4_jbd2.h"
@@ -1827,6 +1828,38 @@ int ext4_destroy_inline_data(handle_t *handle, struct inode *inode)
 	return ret;
 }
 
+int ext4_inline_data_iomap(struct inode *inode, struct iomap *iomap)
+{
+	__u64 addr;
+	int error = -EAGAIN;
+	struct ext4_iloc iloc;
+
+	down_read(&EXT4_I(inode)->xattr_sem);
+	if (!ext4_has_inline_data(inode))
+		goto out;
+
+	error = ext4_get_inode_loc(inode, &iloc);
+	if (error)
+		goto out;
+
+	addr = (__u64)iloc.bh->b_blocknr << inode->i_sb->s_blocksize_bits;
+	addr += (char *)ext4_raw_inode(&iloc) - iloc.bh->b_data;
+	addr += offsetof(struct ext4_inode, i_block);
+
+	brelse(iloc.bh);
+
+	iomap->addr = addr;
+	iomap->offset = 0;
+	iomap->length = min_t(loff_t, ext4_get_inline_size(inode),
+			      i_size_read(inode));
+	iomap->type = 0;
+	iomap->flags = IOMAP_F_DATA_INLINE;
+
+out:
+	up_read(&EXT4_I(inode)->xattr_sem);
+	return error;
+}
+
 int ext4_inline_data_fiemap(struct inode *inode,
 			    struct fiemap_extent_info *fieinfo,
 			    int *has_inline, __u64 start, __u64 len)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index d9e633c12aae..7755f41bdfc3 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3404,8 +3404,20 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 	struct ext4_map_blocks map;
 	int ret;
 
-	if (WARN_ON_ONCE(ext4_has_inline_data(inode)))
-		return -ERANGE;
+
+	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;
+	}
 
 	map.m_lblk = first_block;
 	map.m_len = last_block - first_block + 1;
-- 
2.13.3

[PATCH v2 4/4] ext4: Switch to iomap for SEEK_HOLE / SEEK_DATA

[Andreas Gruenbacher]

From: Christoph Hellwig <hch@lst.de>

Switch to the iomap_seek_hole and iomap_seek_data helpers for
implementing lseek SEEK_HOLE / SEEK_DATA, and remove all the code that
isn't needed any more.

Note that with this patch ext4 will now always depend on the iomap code
instead of only when CONFIG_DAX is enabled, and it requires adding a
call into the extent status tree for iomap_begin as well to properly
deal with delalloc extents.

Signed-off-by: Christoph Hellwig <hch@lst.de>
[Fixes and cleanups by Andreas]
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
 fs/ext4/Kconfig |   1 +
 fs/ext4/ext4.h  |   3 -
 fs/ext4/file.c  | 263 +++-----------------------------------------------------
 fs/ext4/inode.c | 131 +++++++++++-----------------
 4 files changed, 65 insertions(+), 333 deletions(-)

diff --git a/fs/ext4/Kconfig b/fs/ext4/Kconfig
index e38039fd96ff..73b850f5659c 100644
--- a/fs/ext4/Kconfig
+++ b/fs/ext4/Kconfig
@@ -37,6 +37,7 @@ config EXT4_FS
 	select CRC16
 	select CRYPTO
 	select CRYPTO_CRC32C
+	select FS_IOMAP
 	help
 	  This is the next generation of the ext3 filesystem.
 
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index ae3e4a25821a..6fd1fe7456eb 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2515,9 +2515,6 @@ extern void ext4_da_update_reserve_space(struct inode *inode,
 					int used, int quota_claim);
 extern int ext4_issue_zeroout(struct inode *inode, ext4_lblk_t lblk,
 			      ext4_fsblk_t pblk, ext4_lblk_t len);
-extern int ext4_get_next_extent(struct inode *inode, ext4_lblk_t lblk,
-				unsigned int map_len,
-				struct extent_status *result);
 
 /* indirect.c */
 extern int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 57dcaea762c3..3958cd1343a9 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -20,6 +20,7 @@
 
 #include <linux/time.h>
 #include <linux/fs.h>
+#include <linux/iomap.h>
 #include <linux/mount.h>
 #include <linux/path.h>
 #include <linux/dax.h>
@@ -438,248 +439,6 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
 }
 
 /*
- * Here we use ext4_map_blocks() to get a block mapping for a extent-based
- * file rather than ext4_ext_walk_space() because we can introduce
- * SEEK_DATA/SEEK_HOLE for block-mapped and extent-mapped file at the same
- * function.  When extent status tree has been fully implemented, it will
- * track all extent status for a file and we can directly use it to
- * retrieve the offset for SEEK_DATA/SEEK_HOLE.
- */
-
-/*
- * When we retrieve the offset for SEEK_DATA/SEEK_HOLE, we would need to
- * lookup page cache to check whether or not there has some data between
- * [startoff, endoff] because, if this range contains an unwritten extent,
- * we determine this extent as a data or a hole according to whether the
- * page cache has data or not.
- */
-static int ext4_find_unwritten_pgoff(struct inode *inode,
-				     int whence,
-				     ext4_lblk_t end_blk,
-				     loff_t *offset)
-{
-	struct pagevec pvec;
-	unsigned int blkbits;
-	pgoff_t index;
-	pgoff_t end;
-	loff_t endoff;
-	loff_t startoff;
-	loff_t lastoff;
-	int found = 0;
-
-	blkbits = inode->i_sb->s_blocksize_bits;
-	startoff = *offset;
-	lastoff = startoff;
-	endoff = (loff_t)end_blk << blkbits;
-
-	index = startoff >> PAGE_SHIFT;
-	end = (endoff - 1) >> PAGE_SHIFT;
-
-	pagevec_init(&pvec, 0);
-	do {
-		int i;
-		unsigned long nr_pages;
-
-		nr_pages = pagevec_lookup_range(&pvec, inode->i_mapping,
-					&index, end);
-		if (nr_pages == 0)
-			break;
-
-		for (i = 0; i < nr_pages; i++) {
-			struct page *page = pvec.pages[i];
-			struct buffer_head *bh, *head;
-
-			/*
-			 * If current offset is smaller than the page offset,
-			 * there is a hole at this offset.
-			 */
-			if (whence == SEEK_HOLE && lastoff < endoff &&
-			    lastoff < page_offset(pvec.pages[i])) {
-				found = 1;
-				*offset = lastoff;
-				goto out;
-			}
-
-			lock_page(page);
-
-			if (unlikely(page->mapping != inode->i_mapping)) {
-				unlock_page(page);
-				continue;
-			}
-
-			if (!page_has_buffers(page)) {
-				unlock_page(page);
-				continue;
-			}
-
-			if (page_has_buffers(page)) {
-				lastoff = page_offset(page);
-				bh = head = page_buffers(page);
-				do {
-					if (lastoff + bh->b_size <= startoff)
-						goto next;
-					if (buffer_uptodate(bh) ||
-					    buffer_unwritten(bh)) {
-						if (whence == SEEK_DATA)
-							found = 1;
-					} else {
-						if (whence == SEEK_HOLE)
-							found = 1;
-					}
-					if (found) {
-						*offset = max_t(loff_t,
-							startoff, lastoff);
-						unlock_page(page);
-						goto out;
-					}
-next:
-					lastoff += bh->b_size;
-					bh = bh->b_this_page;
-				} while (bh != head);
-			}
-
-			lastoff = page_offset(page) + PAGE_SIZE;
-			unlock_page(page);
-		}
-
-		pagevec_release(&pvec);
-	} while (index <= end);
-
-	/* There are no pages upto endoff - that would be a hole in there. */
-	if (whence == SEEK_HOLE && lastoff < endoff) {
-		found = 1;
-		*offset = lastoff;
-	}
-out:
-	pagevec_release(&pvec);
-	return found;
-}
-
-/*
- * ext4_seek_data() retrieves the offset for SEEK_DATA.
- */
-static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
-{
-	struct inode *inode = file->f_mapping->host;
-	struct extent_status es;
-	ext4_lblk_t start, last, end;
-	loff_t dataoff, isize;
-	int blkbits;
-	int ret;
-
-	inode_lock(inode);
-
-	isize = i_size_read(inode);
-	if (offset < 0 || offset >= isize) {
-		inode_unlock(inode);
-		return -ENXIO;
-	}
-
-	blkbits = inode->i_sb->s_blocksize_bits;
-	start = offset >> blkbits;
-	last = start;
-	end = isize >> blkbits;
-	dataoff = offset;
-
-	do {
-		ret = ext4_get_next_extent(inode, last, end - last + 1, &es);
-		if (ret <= 0) {
-			/* No extent found -> no data */
-			if (ret == 0)
-				ret = -ENXIO;
-			inode_unlock(inode);
-			return ret;
-		}
-
-		last = es.es_lblk;
-		if (last != start)
-			dataoff = (loff_t)last << blkbits;
-		if (!ext4_es_is_unwritten(&es))
-			break;
-
-		/*
-		 * If there is a unwritten extent at this offset,
-		 * it will be as a data or a hole according to page
-		 * cache that has data or not.
-		 */
-		if (ext4_find_unwritten_pgoff(inode, SEEK_DATA,
-					      es.es_lblk + es.es_len, &dataoff))
-			break;
-		last += es.es_len;
-		dataoff = (loff_t)last << blkbits;
-		cond_resched();
-	} while (last <= end);
-
-	inode_unlock(inode);
-
-	if (dataoff > isize)
-		return -ENXIO;
-
-	return vfs_setpos(file, dataoff, maxsize);
-}
-
-/*
- * ext4_seek_hole() retrieves the offset for SEEK_HOLE.
- */
-static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
-{
-	struct inode *inode = file->f_mapping->host;
-	struct extent_status es;
-	ext4_lblk_t start, last, end;
-	loff_t holeoff, isize;
-	int blkbits;
-	int ret;
-
-	inode_lock(inode);
-
-	isize = i_size_read(inode);
-	if (offset < 0 || offset >= isize) {
-		inode_unlock(inode);
-		return -ENXIO;
-	}
-
-	blkbits = inode->i_sb->s_blocksize_bits;
-	start = offset >> blkbits;
-	last = start;
-	end = isize >> blkbits;
-	holeoff = offset;
-
-	do {
-		ret = ext4_get_next_extent(inode, last, end - last + 1, &es);
-		if (ret < 0) {
-			inode_unlock(inode);
-			return ret;
-		}
-		/* Found a hole? */
-		if (ret == 0 || es.es_lblk > last) {
-			if (last != start)
-				holeoff = (loff_t)last << blkbits;
-			break;
-		}
-		/*
-		 * If there is a unwritten extent at this offset,
-		 * it will be as a data or a hole according to page
-		 * cache that has data or not.
-		 */
-		if (ext4_es_is_unwritten(&es) &&
-		    ext4_find_unwritten_pgoff(inode, SEEK_HOLE,
-					      last + es.es_len, &holeoff))
-			break;
-
-		last += es.es_len;
-		holeoff = (loff_t)last << blkbits;
-		cond_resched();
-	} while (last <= end);
-
-	inode_unlock(inode);
-
-	if (holeoff > isize)
-		holeoff = isize;
-
-	return vfs_setpos(file, holeoff, maxsize);
-}
-
-/*
  * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
  * by calling generic_file_llseek_size() with the appropriate maxbytes
  * value for each.
@@ -695,18 +454,24 @@ loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
 		maxbytes = inode->i_sb->s_maxbytes;
 
 	switch (whence) {
-	case SEEK_SET:
-	case SEEK_CUR:
-	case SEEK_END:
+	default:
 		return generic_file_llseek_size(file, offset, whence,
 						maxbytes, i_size_read(inode));
-	case SEEK_DATA:
-		return ext4_seek_data(file, offset, maxbytes);
 	case SEEK_HOLE:
-		return ext4_seek_hole(file, offset, maxbytes);
+		inode_lock_shared(inode);
+		offset = iomap_seek_hole(inode, offset, &ext4_iomap_ops);
+		inode_unlock_shared(inode);
+		break;
+	case SEEK_DATA:
+		inode_lock_shared(inode);
+		offset = iomap_seek_data(inode, offset, &ext4_iomap_ops);
+		inode_unlock_shared(inode);
+		break;
 	}
 
-	return -EINVAL;
+	if (offset < 0)
+		return offset;
+	return vfs_setpos(file, offset, maxbytes);
 }
 
 const struct file_operations ext4_file_operations = {
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 7755f41bdfc3..7264d09d3876 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3393,7 +3393,6 @@ static int ext4_releasepage(struct page *page, gfp_t wait)
 		return try_to_free_buffers(page);
 }
 
-#ifdef CONFIG_FS_DAX
 static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 			    unsigned flags, struct iomap *iomap)
 {
@@ -3402,6 +3401,7 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 	unsigned long first_block = offset >> blkbits;
 	unsigned long last_block = (offset + length - 1) >> blkbits;
 	struct ext4_map_blocks map;
+	bool delalloc = false;
 	int ret;
 
 
@@ -3422,9 +3422,38 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 	map.m_lblk = first_block;
 	map.m_len = last_block - first_block + 1;
 
-	if (!(flags & IOMAP_WRITE)) {
+	if (flags & IOMAP_REPORT) {
 		ret = ext4_map_blocks(NULL, inode, &map, 0);
-	} else {
+		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_delayed_extent_range(inode, 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_pblk = ext4_es_pblock(&es) + offs;
+				map.m_len = es.es_len - offs;
+				if (ext4_es_is_unwritten(&es))
+					map.m_flags |= EXT4_MAP_UNWRITTEN;
+				if (ext4_es_is_delayed(&es))
+					delalloc = true;
+				ret = 1;
+			}
+		}
+	} else if (flags & IOMAP_WRITE) {
 		int dio_credits;
 		handle_t *handle;
 		int retries = 0;
@@ -3475,32 +3504,41 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 			}
 		}
 		ext4_journal_stop(handle);
+	} else {
+		ret = ext4_map_blocks(NULL, inode, &map, 0);
+		if (ret < 0)
+			return ret;
 	}
 
 	iomap->flags = 0;
 	iomap->bdev = inode->i_sb->s_bdev;
 	iomap->dax_dev = sbi->s_daxdev;
 	iomap->offset = first_block << blkbits;
+	iomap->length = (u64)map.m_len << blkbits;
 
 	if (ret == 0) {
 		iomap->type = IOMAP_HOLE;
 		iomap->addr = IOMAP_NULL_ADDR;
-		iomap->length = (u64)map.m_len << blkbits;
 	} else {
-		if (map.m_flags & EXT4_MAP_MAPPED) {
-			iomap->type = IOMAP_MAPPED;
-		} else if (map.m_flags & EXT4_MAP_UNWRITTEN) {
-			iomap->type = IOMAP_UNWRITTEN;
+		if (delalloc) {
+			iomap->type = IOMAP_DELALLOC;
+			iomap->addr = IOMAP_NULL_ADDR;
 		} else {
-			WARN_ON_ONCE(1);
-			return -EIO;
+			if (map.m_flags & EXT4_MAP_MAPPED) {
+				iomap->type = IOMAP_MAPPED;
+			} else if (map.m_flags & EXT4_MAP_UNWRITTEN) {
+				iomap->type = IOMAP_UNWRITTEN;
+			} else {
+				WARN_ON_ONCE(1);
+				return -EIO;
+			}
+			iomap->addr = (u64)map.m_pblk << blkbits;
 		}
-		iomap->addr = (u64)map.m_pblk << blkbits;
-		iomap->length = (u64)map.m_len << blkbits;
 	}
 
 	if (map.m_flags & EXT4_MAP_NEW)
 		iomap->flags |= IOMAP_F_NEW;
+
 	return 0;
 }
 
@@ -3561,8 +3599,6 @@ const struct iomap_ops ext4_iomap_ops = {
 	.iomap_end		= ext4_iomap_end,
 };
 
-#endif
-
 static int ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
 			    ssize_t size, void *private)
 {
@@ -6118,70 +6154,3 @@ int ext4_filemap_fault(struct vm_fault *vmf)
 
 	return err;
 }
-
-/*
- * Find the first extent at or after @lblk in an inode that is not a hole.
- * Search for @map_len blocks at most. The extent is returned in @result.
- *
- * The function returns 1 if we found an extent. The function returns 0 in
- * case there is no extent at or after @lblk and in that case also sets
- * @result->es_len to 0. In case of error, the error code is returned.
- */
-int ext4_get_next_extent(struct inode *inode, ext4_lblk_t lblk,
-			 unsigned int map_len, struct extent_status *result)
-{
-	struct ext4_map_blocks map;
-	struct extent_status es = {};
-	int ret;
-
-	map.m_lblk = lblk;
-	map.m_len = map_len;
-
-	/*
-	 * For non-extent based files this loop may iterate several times since
-	 * we do not determine full hole size.
-	 */
-	while (map.m_len > 0) {
-		ret = ext4_map_blocks(NULL, inode, &map, 0);
-		if (ret < 0)
-			return ret;
-		/* There's extent covering m_lblk? Just return it. */
-		if (ret > 0) {
-			int status;
-
-			ext4_es_store_pblock(result, map.m_pblk);
-			result->es_lblk = map.m_lblk;
-			result->es_len = map.m_len;
-			if (map.m_flags & EXT4_MAP_UNWRITTEN)
-				status = EXTENT_STATUS_UNWRITTEN;
-			else
-				status = EXTENT_STATUS_WRITTEN;
-			ext4_es_store_status(result, status);
-			return 1;
-		}
-		ext4_es_find_delayed_extent_range(inode, map.m_lblk,
-						  map.m_lblk + map.m_len - 1,
-						  &es);
-		/* Is delalloc data before next block in extent tree? */
-		if (es.es_len && es.es_lblk < map.m_lblk + map.m_len) {
-			ext4_lblk_t offset = 0;
-
-			if (es.es_lblk < lblk)
-				offset = lblk - es.es_lblk;
-			result->es_lblk = es.es_lblk + offset;
-			ext4_es_store_pblock(result,
-					     ext4_es_pblock(&es) + offset);
-			result->es_len = es.es_len - offset;
-			ext4_es_store_status(result, ext4_es_status(&es));
-
-			return 1;
-		}
-		/* There's a hole at m_lblk, advance us after it */
-		map.m_lblk += map.m_len;
-		map_len -= map.m_len;
-		map.m_len = map_len;
-		cond_resched();
-	}
-	result->es_len = 0;
-	return 0;
-}
-- 
2.13.3

Re: [PATCH v2 4/4] ext4: Switch to iomap for SEEK_HOLE / SEEK_DATA

[Jan Kara]

On Thu 14-09-17 11:50:47, Andreas Gruenbacher wrote:
> @@ -3422,9 +3422,38 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
>  	map.m_lblk = first_block;
>  	map.m_len = last_block - first_block + 1;
>  
> -	if (!(flags & IOMAP_WRITE)) {
> +	if (flags & IOMAP_REPORT) {
>  		ret = ext4_map_blocks(NULL, inode, &map, 0);
> -	} else {
> +		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_delayed_extent_range(inode, 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_pblk = ext4_es_pblock(&es) + offs;
> +				map.m_len = es.es_len - offs;
> +				if (ext4_es_is_unwritten(&es))
> +					map.m_flags |= EXT4_MAP_UNWRITTEN;

This is not possible. If there is unwritten extent at map->m_lblk, then
ext4_map_blocks() could not have possibly returned 0. So just delete this
condition and set map.m_pblk to 0 since delalloc extent has no physical
possition.

> +				if (ext4_es_is_delayed(&es))
> +					delalloc = true;

Also ext4_es_is_delayed(&es) is guaranteed to be true since you've looked
it up by ext4_es_find_delayed_extent_range(). So just set delalloc = true
unconditionally.

Otherwise the patch looks good so after fixing up these small issues feel
free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

Re: [PATCH v2 4/4] ext4: Switch to iomap for SEEK_HOLE / SEEK_DATA

[Andreas Grünbacher]

2017-09-14 14:02 GMT+02:00 Jan Kara <jack@suse.cz>:
> On Thu 14-09-17 11:50:47, Andreas Gruenbacher wrote:
>> @@ -3422,9 +3422,38 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
>>       map.m_lblk = first_block;
>>       map.m_len = last_block - first_block + 1;
>>
>> -     if (!(flags & IOMAP_WRITE)) {
>> +     if (flags & IOMAP_REPORT) {
>>               ret = ext4_map_blocks(NULL, inode, &map, 0);
>> -     } else {
>> +             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_delayed_extent_range(inode, 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_pblk = ext4_es_pblock(&es) + offs;
>> +                             map.m_len = es.es_len - offs;
>> +                             if (ext4_es_is_unwritten(&es))
>> +                                     map.m_flags |= EXT4_MAP_UNWRITTEN;
>
> This is not possible. If there is unwritten extent at map->m_lblk, then
> ext4_map_blocks() could not have possibly returned 0. So just delete this
> condition and set map.m_pblk to 0 since delalloc extent has no physical
> position.
>
>> +                             if (ext4_es_is_delayed(&es))
>> +                                     delalloc = true;
>
> Also ext4_es_is_delayed(&es) is guaranteed to be true since you've looked
> it up by ext4_es_find_delayed_extent_range(). So just set delalloc = true
> unconditionally.

Since map.m_pblk is never used in the delalloc case, we can leave it
undefined above as well.

> Otherwise the patch looks good so after fixing up these small issues feel
> free to add:
>
> Reviewed-by: Jan Kara <jack@suse.cz>

Thanks,
Andreas

Re: [PATCH v2 4/4] ext4: Switch to iomap for SEEK_HOLE / SEEK_DATA

[Jan Kara]

On Thu 14-09-17 14:47:28, Andreas Gr�nbacher wrote:
> 2017-09-14 14:02 GMT+02:00 Jan Kara <jack@suse.cz>:
> > On Thu 14-09-17 11:50:47, Andreas Gruenbacher wrote:
> >> @@ -3422,9 +3422,38 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> >>       map.m_lblk = first_block;
> >>       map.m_len = last_block - first_block + 1;
> >>
> >> -     if (!(flags & IOMAP_WRITE)) {
> >> +     if (flags & IOMAP_REPORT) {
> >>               ret = ext4_map_blocks(NULL, inode, &map, 0);
> >> -     } else {
> >> +             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_delayed_extent_range(inode, 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_pblk = ext4_es_pblock(&es) + offs;
> >> +                             map.m_len = es.es_len - offs;
> >> +                             if (ext4_es_is_unwritten(&es))
> >> +                                     map.m_flags |= EXT4_MAP_UNWRITTEN;
> >
> > This is not possible. If there is unwritten extent at map->m_lblk, then
> > ext4_map_blocks() could not have possibly returned 0. So just delete this
> > condition and set map.m_pblk to 0 since delalloc extent has no physical
> > position.
> >
> >> +                             if (ext4_es_is_delayed(&es))
> >> +                                     delalloc = true;
> >
> > Also ext4_es_is_delayed(&es) is guaranteed to be true since you've looked
> > it up by ext4_es_find_delayed_extent_range(). So just set delalloc = true
> > unconditionally.
> 
> Since map.m_pblk is never used in the delalloc case, we can leave it
> undefined above as well.

Yeah, that's fine by me as well.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

Re: [PATCH v2 4/4] ext4: Switch to iomap for SEEK_HOLE / SEEK_DATA

[Jan Kara]

On Thu 14-09-17 14:47:28, Andreas Grünbacher wrote:
> 2017-09-14 14:02 GMT+02:00 Jan Kara <jack@suse.cz>:
> > On Thu 14-09-17 11:50:47, Andreas Gruenbacher wrote:
> >> @@ -3422,9 +3422,38 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> >>       map.m_lblk = first_block;
> >>       map.m_len = last_block - first_block + 1;
> >>
> >> -     if (!(flags & IOMAP_WRITE)) {
> >> +     if (flags & IOMAP_REPORT) {
> >>               ret = ext4_map_blocks(NULL, inode, &map, 0);
> >> -     } else {
> >> +             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_delayed_extent_range(inode, 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_pblk = ext4_es_pblock(&es) + offs;
> >> +                             map.m_len = es.es_len - offs;
> >> +                             if (ext4_es_is_unwritten(&es))
> >> +                                     map.m_flags |= EXT4_MAP_UNWRITTEN;
> >
> > This is not possible. If there is unwritten extent at map->m_lblk, then
> > ext4_map_blocks() could not have possibly returned 0. So just delete this
> > condition and set map.m_pblk to 0 since delalloc extent has no physical
> > position.
> >
> >> +                             if (ext4_es_is_delayed(&es))
> >> +                                     delalloc = true;
> >
> > Also ext4_es_is_delayed(&es) is guaranteed to be true since you've looked
> > it up by ext4_es_find_delayed_extent_range(). So just set delalloc = true
> > unconditionally.
> 
> Since map.m_pblk is never used in the delalloc case, we can leave it
> undefined above as well.

Yeah, that's fine by me as well.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

Re: [PATCH v2 3/4] ext4: Add iomap support for inline data

[Theodore Ts'o]

On Thu, Sep 14, 2017 at 11:50:46AM +0200, Andreas Gruenbacher wrote:
> +int ext4_inline_data_iomap(struct inode *inode, struct iomap *iomap)
> +{
> +	__u64 addr;
> +	int error = -EAGAIN;
> +	struct ext4_iloc iloc;
> +
> +	down_read(&EXT4_I(inode)->xattr_sem);
> +	if (!ext4_has_inline_data(inode))
> +		goto out;
	....
> +out:
> +	up_read(&EXT4_I(inode)->xattr_sem);
> +	return error;
> +}


If we race with the inline data flag getting cleared,
ext4_iomap_begin() will return with -EAGAIN.  As near as I can tell,
this will get reflected all the way up to userspace, instead of having
the retry happen in the kernel.  Is this intentional?

It looks like a user visible change, no?

						- Ted

Re: [PATCH v2 3/4] ext4: Add iomap support for inline data

[Andreas Gruenbacher]

On Thu, Sep 28, 2017 at 7:57 PM, Theodore Ts'o <tytso@mit.edu> wrote:
> On Thu, Sep 14, 2017 at 11:50:46AM +0200, Andreas Gruenbacher wrote:
>> +int ext4_inline_data_iomap(struct inode *inode, struct iomap *iomap)
>> +{
>> +     __u64 addr;
>> +     int error = -EAGAIN;
>> +     struct ext4_iloc iloc;
>> +
>> +     down_read(&EXT4_I(inode)->xattr_sem);
>> +     if (!ext4_has_inline_data(inode))
>> +             goto out;
>         ....
>> +out:
>> +     up_read(&EXT4_I(inode)->xattr_sem);
>> +     return error;
>> +}
>
>
> If we race with the inline data flag getting cleared,
> ext4_iomap_begin() will return with -EAGAIN.

Actually, in that case, ext4_iomap_begin will treat the file as non-inline.
It will not return -EAGAIN.

> As near as I can tell,
> this will get reflected all the way up to userspace, instead of having
> the retry happen in the kernel.  Is this intentional?
>
> It looks like a user visible change, no?

That would be a bug.

Thanks,
Andreas

Re: [PATCH v2 3/4] ext4: Add iomap support for inline data

[Theodore Ts'o]

On Mon, Oct 02, 2017 at 04:39:59PM +0200, Andreas Gruenbacher wrote:
> > If we race with the inline data flag getting cleared,
> > ext4_iomap_begin() will return with -EAGAIN.
> 
> Actually, in that case, ext4_iomap_begin will treat the file as non-inline.
> It will not return -EAGAIN.

Ah, thanks, I missed that.

					- Ted