[PATCH 0/5 v4] fiemap: introduce EXTENT_DATA_COMPRESSED flag

[PATCH 0/5 v4] fiemap: introduce EXTENT_DATA_COMPRESSED flag

[David Sterba]

The original FIEMAP patch did not define this bit, btrfs will make use of
it.  The defined constant maintains the same value as originally proposed.

Currently, the 'filefrag' utility has no way to recognize and denote a
compressed extent. As implemented in btrfs right now, the compression step
splits a big extent into smaller chunks and this is reported as a heavily
fragmented file. Adding the flag to filefrag will at least give some
explanation why, this has been confusing users for some time already.

fiemap_fill_next_extent is extended and takes argument to fill the physical
length.

V4:
The physical length is always set and equal to logical, or different and
then sets the COMPRESSED flag.
fiemap_extent::fe_length renamed to fe_logi_length

V3:
Based on feedback from Andreas, implement #1 from V2, current users of
fiemap_fill_next_extent (fs/, ext4, gfs2, ocfs2, nilfs2, xfs) updated
accordingly, no functional change.

V2:
Based on feedback from Andreas, the fiemap_extent is now able to hold the
physical extent length, to be filled by the filesystem callback.


1) extend fiemap_fill_next_extent to take phys_length and update all
   users (ext4, gfs2, ocfs2, nilfs2, xfs)

David Sterba (5):
  fiemap: fix comment at EXTENT_DATA_ENCRYPTED
  fiemap: add EXTENT_DATA_COMPRESSED flag
  btrfs: set FIEMAP_EXTENT_DATA_COMPRESSED for compressed extents
  Documentation/fiemap: Document the DATA_COMPRESSED flag
  fiemap: rename fe_length to fe_logi_length

 Documentation/filesystems/fiemap.txt | 19 +++++++++++++++----
 fs/btrfs/extent_io.c                 |  8 ++++++--
 fs/ext4/extents.c                    |  3 ++-
 fs/ext4/inline.c                     |  2 +-
 fs/gfs2/inode.c                      |  2 +-
 fs/ioctl.c                           | 29 ++++++++++++++++++++++-------
 fs/nilfs2/inode.c                    |  8 +++++---
 fs/ocfs2/extent_map.c                |  4 ++--
 fs/xfs/xfs_iops.c                    |  2 +-
 include/linux/fs.h                   |  2 +-
 include/uapi/linux/fiemap.h          | 13 ++++++++++---
 11 files changed, 66 insertions(+), 26 deletions(-)

-- 
1.8.4.5

[PATCH 2/5] fiemap: add EXTENT_DATA_COMPRESSED flag

[David Sterba]

This flag was not accepted when fiemap was proposed [2] due to lack of
in-kernel users. Btrfs has compression for a long time and we'd like to
see that an extent is compressed in the output of 'filefrag' utility
once it's taught about it.

For that purpose, a reserved field from fiemap_extent is used to let the
filesystem store along the physcial extent length when the flag is set.
This keeps compatibility with applications that use FIEMAP.

Extend arguments of fiemap_fill_next_extent and update all users.

[1] http://article.gmane.org/gmane.comp.file-systems.ext4/8871
[2] http://thread.gmane.org/gmane.comp.file-systems.ext4/8870
[3] http://thread.gmane.org/gmane.linux.file-systems/77632 (v1)
[4] http://www.spinics.net/lists/linux-fsdevel/msg69078.html (v2)

Cc: Al Viro <viro@zeniv.linux.org.uk>
CC: Andreas Dilger <adilger@dilger.ca>
CC: Chris Mason <clm@fb.com>
CC: Christoph Hellwig <hch@infradead.org>
CC  KONISHI Ryusuke <konishi.ryusuke@lab.ntt.co.jp>
CC: Mark Fasheh <mfasheh@suse.com>
CC: Steven Whitehouse <swhiteho@redhat.com>
CC: "Theodore Ts'o" <tytso@mit.edu>
CC: Ben Myers <bpm@sgi.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
---
 fs/btrfs/extent_io.c        |  2 +-
 fs/ext4/extents.c           |  3 ++-
 fs/ext4/inline.c            |  2 +-
 fs/gfs2/inode.c             |  2 +-
 fs/ioctl.c                  | 27 +++++++++++++++++++++------
 fs/nilfs2/inode.c           |  8 +++++---
 fs/ocfs2/extent_map.c       |  4 ++--
 fs/xfs/xfs_iops.c           |  2 +-
 include/linux/fs.h          |  2 +-
 include/uapi/linux/fiemap.h |  8 +++++++-
 10 files changed, 42 insertions(+), 18 deletions(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index a389820d158b..eec118bf77ae 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4357,7 +4357,7 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 			end = 1;
 		}
 		ret = fiemap_fill_next_extent(fieinfo, em_start, disko,
-					      em_len, flags);
+					      em_len, em_len, flags);
 		if (ret)
 			goto out_free;
 	}
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 4da228a0e6d0..0bdd173ac728 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2253,6 +2253,7 @@ static int ext4_fill_fiemap_extents(struct inode *inode,
 				(__u64)es.es_lblk << blksize_bits,
 				(__u64)es.es_pblk << blksize_bits,
 				(__u64)es.es_len << blksize_bits,
+				(__u64)es.es_len << blksize_bits,
 				flags);
 			if (err < 0)
 				break;
@@ -5125,7 +5126,7 @@ static int ext4_xattr_fiemap(struct inode *inode,
 
 	if (physical)
 		error = fiemap_fill_next_extent(fieinfo, 0, physical,
-						length, flags);
+						length, length, flags);
 	return (error < 0 ? error : 0);
 }
 
diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index 645205d8ada6..3825ff9dc40d 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -1825,7 +1825,7 @@ int ext4_inline_data_fiemap(struct inode *inode,
 
 	if (physical)
 		error = fiemap_fill_next_extent(fieinfo, 0, physical,
-						length, flags);
+						length, length, flags);
 	brelse(iloc.bh);
 out:
 	up_read(&EXT4_I(inode)->xattr_sem);
diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index e62e59477884..5b45cf4e5465 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -1931,7 +1931,7 @@ static int gfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 			len = size - start;
 		if (start < size)
 			ret = fiemap_fill_next_extent(fieinfo, start, phys,
-						      len, flags);
+						      len, len, flags);
 		if (ret == 1)
 			ret = 0;
 	} else {
diff --git a/fs/ioctl.c b/fs/ioctl.c
index 8ac3fad36192..24a9d912d1e6 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -70,20 +70,26 @@ static int ioctl_fibmap(struct file *filp, int __user *p)
  * @logical:	Extent logical start offset, in bytes
  * @phys:	Extent physical start offset, in bytes
  * @len:	Extent length, in bytes
+ * @phys_len:   Physical extent length in bytes
  * @flags:	FIEMAP_EXTENT flags that describe this extent
  *
  * Called from file system ->fiemap callback. Will populate extent
  * info as passed in via arguments and copy to user memory. On
  * success, extent count on fieinfo is incremented.
  *
+ * Extents without any encoding must set the physical and logical length
+ * to the same value. Otherwise, set flags to FIEMAP_EXTENT_ENCODED
+ * and possibly specify encoding type.
+ *
  * Returns 0 on success, -errno on error, 1 if this was the last
  * extent that will fit in user array.
  */
 #define SET_UNKNOWN_FLAGS	(FIEMAP_EXTENT_DELALLOC)
-#define SET_NO_UNMOUNTED_IO_FLAGS	(FIEMAP_EXTENT_DATA_ENCRYPTED)
+#define SET_NO_UNMOUNTED_IO_FLAGS	(FIEMAP_EXTENT_DATA_ENCRYPTED | \
+					 FIEMAP_EXTENT_DATA_COMPRESSED)
 #define SET_NOT_ALIGNED_FLAGS	(FIEMAP_EXTENT_DATA_TAIL|FIEMAP_EXTENT_DATA_INLINE)
 int fiemap_fill_next_extent(struct fiemap_extent_info *fieinfo, u64 logical,
-			    u64 phys, u64 len, u32 flags)
+			    u64 phys, u64 len, u64 phys_len, u32 flags)
 {
 	struct fiemap_extent extent;
 	struct fiemap_extent __user *dest = fieinfo->fi_extents_start;
@@ -110,6 +116,14 @@ int fiemap_fill_next_extent(struct fiemap_extent_info *fieinfo, u64 logical,
 	extent.fe_length = len;
 	extent.fe_flags = flags;
 
+	WARN_ONCE((flags & FIEMAP_EXTENT_DATA_COMPRESSED)
+		&& !(flags & FIEMAP_EXTENT_ENCODED));
+	WARN_ONCE(phys_len != len && !(flags & FIEMAP_EXTENT_DATA_COMPRESSED),
+		"physical length %llu != logical length %llu without = DATA_COMPRESSED\n",
+		phys_len, len);
+
+	extent.fe_phys_length = phys_len;
+
 	dest += fieinfo->fi_extents_mapped;
 	if (copy_to_user(dest, &extent, sizeof(extent)))
 		return -EFAULT;
@@ -318,10 +332,11 @@ int __generic_block_fiemap(struct inode *inode,
 				flags = FIEMAP_EXTENT_MERGED|FIEMAP_EXTENT_LAST;
 				ret = fiemap_fill_next_extent(fieinfo, logical,
 							      phys, size,
-							      flags);
+							      size, flags);
 			} else if (size) {
 				ret = fiemap_fill_next_extent(fieinfo, logical,
-							      phys, size, flags);
+							      phys, size,
+							      size, flags);
 				size = 0;
 			}
 
@@ -347,7 +362,7 @@ int __generic_block_fiemap(struct inode *inode,
 			if (start_blk > last_blk && !whole_file) {
 				ret = fiemap_fill_next_extent(fieinfo, logical,
 							      phys, size,
-							      flags);
+							      size, flags);
 				break;
 			}
 
@@ -358,7 +373,7 @@ int __generic_block_fiemap(struct inode *inode,
 			if (size) {
 				ret = fiemap_fill_next_extent(fieinfo, logical,
 							      phys, size,
-							      flags);
+							      size, flags);
 				if (ret)
 					break;
 			}
diff --git a/fs/nilfs2/inode.c b/fs/nilfs2/inode.c
index 6252b173a465..a74d3a0e670a 100644
--- a/fs/nilfs2/inode.c
+++ b/fs/nilfs2/inode.c
@@ -1017,7 +1017,8 @@ int nilfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 			if (size) {
 				/* End of the current extent */
 				ret = fiemap_fill_next_extent(
-					fieinfo, logical, phys, size, flags);
+					fieinfo, logical, phys, size, size,
+					flags);
 				if (ret)
 					break;
 			}
@@ -1067,7 +1068,8 @@ int nilfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 					flags |= FIEMAP_EXTENT_LAST;
 
 				ret = fiemap_fill_next_extent(
-					fieinfo, logical, phys, size, flags);
+					fieinfo, logical, phys, size,
+					size, flags);
 				if (ret)
 					break;
 				size = 0;
@@ -1083,7 +1085,7 @@ int nilfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 					/* Terminate the current extent */
 					ret = fiemap_fill_next_extent(
 						fieinfo, logical, phys, size,
-						flags);
+						size, flags);
 					if (ret || blkoff > end_blkoff)
 						break;
 
diff --git a/fs/ocfs2/extent_map.c b/fs/ocfs2/extent_map.c
index 767370b656ca..45c95aa2a00f 100644
--- a/fs/ocfs2/extent_map.c
+++ b/fs/ocfs2/extent_map.c
@@ -736,7 +736,7 @@ static int ocfs2_fiemap_inline(struct inode *inode, struct buffer_head *di_bh,
 					 id2.i_data.id_data);
 
 		ret = fiemap_fill_next_extent(fieinfo, 0, phys, id_count,
-					      flags);
+					      id_count, flags);
 		if (ret < 0)
 			return ret;
 	}
@@ -809,7 +809,7 @@ int ocfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		virt_bytes = (u64)le32_to_cpu(rec.e_cpos) << osb->s_clustersize_bits;
 
 		ret = fiemap_fill_next_extent(fieinfo, virt_bytes, phys_bytes,
-					      len_bytes, fe_flags);
+					      len_bytes, len_bytes, fe_flags);
 		if (ret)
 			break;
 
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 205613a06068..eeef5381debb 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -1030,7 +1030,7 @@ xfs_fiemap_format(
 		fiemap_flags |= FIEMAP_EXTENT_LAST;
 
 	error = fiemap_fill_next_extent(fieinfo, logical, physical,
-					length, fiemap_flags);
+					length, length, fiemap_flags);
 	if (error > 0) {
 		error = 0;
 		*full = 1;	/* user array now full */
diff --git a/include/linux/fs.h b/include/linux/fs.h
index e11d60cc867b..609e1d72c3e0 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1412,7 +1412,7 @@ struct fiemap_extent_info {
 							fiemap_extent array */
 };
 int fiemap_fill_next_extent(struct fiemap_extent_info *info, u64 logical,
-			    u64 phys, u64 len, u32 flags);
+			    u64 phys, u64 len, u64 phys_len, u32 flags);
 int fiemap_check_flags(struct fiemap_extent_info *fieinfo, u32 fs_flags);
 
 /*
diff --git a/include/uapi/linux/fiemap.h b/include/uapi/linux/fiemap.h
index 93abfcd9ac47..11b51887b94a 100644
--- a/include/uapi/linux/fiemap.h
+++ b/include/uapi/linux/fiemap.h
@@ -19,7 +19,9 @@ struct fiemap_extent {
 	__u64 fe_physical; /* physical offset in bytes for the start
 			    * of the extent from the beginning of the disk */
 	__u64 fe_length;   /* length in bytes for this extent */
-	__u64 fe_reserved64[2];
+	__u64 fe_phys_length; /* physical length in bytes, may be different from
+                               * fe_length and sets additional extent flags */
+	__u64 fe_reserved64;
 	__u32 fe_flags;    /* FIEMAP_EXTENT_* flags for this extent */
 	__u32 fe_reserved[3];
 };
@@ -50,6 +52,10 @@ struct fiemap {
 						    * Sets EXTENT_UNKNOWN. */
 #define FIEMAP_EXTENT_ENCODED		0x00000008 /* Data can not be read
 						    * while fs is unmounted */
+#define FIEMAP_EXTENT_DATA_COMPRESSED	0x00000040 /* Data is compressed by fs.
+						    * Sets EXTENT_ENCODED and
+						    * the compressed size is
+						    * stored in fe_phys_length */
 #define FIEMAP_EXTENT_DATA_ENCRYPTED	0x00000080 /* Data is encrypted by fs.
 						    * Sets EXTENT_ENCODED */
 #define FIEMAP_EXTENT_NOT_ALIGNED	0x00000100 /* Extent offsets may not be
-- 
1.8.4.5

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