[PATCH 0/3] fiemap extension to add physical extent length

[PATCH 0/3] fiemap extension to add physical extent length

[Sweet Tea Dorminy]

For many years, various btrfs users have written programs to discover
the actual disk space used by files, using root-only interfaces.
However, this information is a great fit for fiemap: it is inherently
tied to extent information, all filesystems can use it, and the
capabilities required for FIEMAP make sense for this additional
information also.

Hence, this patchset adds physical extent length information to fiemap,
and extends btrfs to return it.  This uses some of the reserved padding
in the fiemap extent structure, so programs unaware of the new field
will be unaffected by its presence.

This is based on next-20240307. I've tested the btrfs part of this with
the standard btrfs testing matrix locally, and verified that the physical extent
information returned there is correct, but I'm still waiting on more
tests. Please let me know what you think of the general idea!

Sweet Tea Dorminy (3):
  fs: add physical_length field to fiemap extents
  fs: update fiemap_fill_next_extent() signature
  btrfs: fiemap: return extent physical size

 Documentation/filesystems/fiemap.rst | 29 +++++++++----
 fs/bcachefs/fs.c                     |  6 ++-
 fs/btrfs/extent_io.c                 | 63 +++++++++++++++++-----------
 fs/ext4/extents.c                    |  1 +
 fs/f2fs/data.c                       |  8 ++--
 fs/f2fs/inline.c                     |  3 +-
 fs/ioctl.c                           |  8 ++--
 fs/iomap/fiemap.c                    |  2 +-
 fs/nilfs2/inode.c                    |  8 ++--
 fs/ntfs3/frecord.c                   |  6 ++-
 fs/ocfs2/extent_map.c                |  4 +-
 fs/smb/client/smb2ops.c              |  1 +
 include/linux/fiemap.h               |  2 +-
 include/uapi/linux/fiemap.h          | 24 +++++++----
 14 files changed, 108 insertions(+), 57 deletions(-)


base-commit: 1843e16d2df9d98427ef8045589571749d627cf7
-- 
2.44.0

[PATCH 1/3] fs: add physical_length field to fiemap extents

[Sweet Tea Dorminy]

Some filesystems support compressed extents which have a larger logical
size than physical, and for those filesystems, it can be useful for
userspace to know how much space those extents actually use. For
instance, the compsize [1] tool for btrfs currently uses btrfs-internal,
root-only ioctl to find the actual disk space used by a file; it would
be better and more useful for this information to require fewer
privileges and to be usable on more filesystems. Therefore, use one of
the padding u64s in the fiemap extent structure to return the actual
physical length; and, for now, return this as equal to the logical
length.

[1] https://github.com/kilobyte/compsize

Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
---
 Documentation/filesystems/fiemap.rst | 26 ++++++++++++++++++--------
 fs/ioctl.c                           |  1 +
 include/uapi/linux/fiemap.h          | 24 +++++++++++++++++-------
 3 files changed, 36 insertions(+), 15 deletions(-)

diff --git a/Documentation/filesystems/fiemap.rst b/Documentation/filesystems/fiemap.rst
index 93fc96f760aa..e3e84573b087 100644
--- a/Documentation/filesystems/fiemap.rst
+++ b/Documentation/filesystems/fiemap.rst
@@ -80,14 +80,24 @@ Each extent is described by a single fiemap_extent structure as
 returned in fm_extents::
 
     struct fiemap_extent {
-	    __u64	fe_logical;  /* logical offset in bytes for the start of
-				* the extent */
-	    __u64	fe_physical; /* physical offset in bytes for the start
-				* of the extent */
-	    __u64	fe_length;   /* length in bytes for the extent */
-	    __u64	fe_reserved64[2];
-	    __u32	fe_flags;    /* FIEMAP_EXTENT_* flags for this extent */
-	    __u32	fe_reserved[3];
+            /*
+             * logical offset in bytes for the start of
+             * the extent from the beginning of the file
+             */
+            __u64 fe_logical;
+            /*
+             * physical offset in bytes for the start
+             * of the extent from the beginning of the disk
+             */
+            __u64 fe_physical;
+            /* length in bytes for this extent */
+            __u64 fe_length;
+            /* physical length in bytes for this extent */
+            __u64 fe_physical_length;
+            __u64 fe_reserved64[1];
+            /* FIEMAP_EXTENT_* flags for this extent */
+            __u32 fe_flags;
+            __u32 fe_reserved[3];
     };
 
 All offsets and lengths are in bytes and mirror those on disk.  It is valid
diff --git a/fs/ioctl.c b/fs/ioctl.c
index 1d5abfdf0f22..f8e5d6dfc62d 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -139,6 +139,7 @@ int fiemap_fill_next_extent(struct fiemap_extent_info *fieinfo, u64 logical,
 	extent.fe_logical = logical;
 	extent.fe_physical = phys;
 	extent.fe_length = len;
+	extent.fe_physical_length = len;
 	extent.fe_flags = flags;
 
 	dest += fieinfo->fi_extents_mapped;
diff --git a/include/uapi/linux/fiemap.h b/include/uapi/linux/fiemap.h
index 24ca0c00cae3..fd3c7d380666 100644
--- a/include/uapi/linux/fiemap.h
+++ b/include/uapi/linux/fiemap.h
@@ -15,13 +15,23 @@
 #include <linux/types.h>
 
 struct fiemap_extent {
-	__u64 fe_logical;  /* logical offset in bytes for the start of
-			    * the extent from the beginning of the file */
-	__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];
-	__u32 fe_flags;    /* FIEMAP_EXTENT_* flags for this extent */
+	/*
+	 * logical offset in bytes for the start of
+	 * the extent from the beginning of the file
+	 */
+	__u64 fe_logical;
+	/*
+	 * physical offset in bytes for the start
+	 * of the extent from the beginning of the disk
+	 */
+	__u64 fe_physical;
+	/* length in bytes for this extent */
+	__u64 fe_length;
+	/* physical length in bytes for this extent */
+	__u64 fe_physical_length;
+	__u64 fe_reserved64[1];
+	/* FIEMAP_EXTENT_* flags for this extent */
+	__u32 fe_flags;
 	__u32 fe_reserved[3];
 };
 
-- 
2.44.0

[PATCH 2/3] fs: update fiemap_fill_next_extent() signature

[Sweet Tea Dorminy]

Update the signature of fiemap_fill_next_extent() to allow passing a
physical length, and update all callers to pass the same logical and
physical lengths.

Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
---
 Documentation/filesystems/fiemap.rst | 3 ++-
 fs/bcachefs/fs.c                     | 6 +++++-
 fs/btrfs/extent_io.c                 | 2 +-
 fs/ext4/extents.c                    | 1 +
 fs/f2fs/data.c                       | 8 +++++---
 fs/f2fs/inline.c                     | 3 ++-
 fs/ioctl.c                           | 9 +++++----
 fs/iomap/fiemap.c                    | 2 +-
 fs/nilfs2/inode.c                    | 8 +++++---
 fs/ntfs3/frecord.c                   | 6 ++++--
 fs/ocfs2/extent_map.c                | 4 ++--
 fs/smb/client/smb2ops.c              | 1 +
 include/linux/fiemap.h               | 2 +-
 13 files changed, 35 insertions(+), 20 deletions(-)

diff --git a/Documentation/filesystems/fiemap.rst b/Documentation/filesystems/fiemap.rst
index e3e84573b087..fd0911e65b43 100644
--- a/Documentation/filesystems/fiemap.rst
+++ b/Documentation/filesystems/fiemap.rst
@@ -234,7 +234,8 @@ For each extent in the request range, the file system should call
 the helper function, fiemap_fill_next_extent()::
 
   int fiemap_fill_next_extent(struct fiemap_extent_info *info, u64 logical,
-			      u64 phys, u64 len, u32 flags, u32 dev);
+			      u64 phys, u64 log_len, u64 phys_len, u32 flags,
+                              u32 dev);
 
 fiemap_fill_next_extent() will use the passed values to populate the
 next free extent in the fm_extents array. 'General' extent flags will
diff --git a/fs/bcachefs/fs.c b/fs/bcachefs/fs.c
index 3f073845bbd7..0a030f048fc6 100644
--- a/fs/bcachefs/fs.c
+++ b/fs/bcachefs/fs.c
@@ -927,7 +927,9 @@ static int bch2_fill_extent(struct bch_fs *c,
 			ret = fiemap_fill_next_extent(info,
 						bkey_start_offset(k.k) << 9,
 						offset << 9,
-						k.k->size << 9, flags|flags2);
+						k.k->size << 9,
+						k.k->size << 9,
+						flags|flags2);
 			if (ret)
 				return ret;
 		}
@@ -937,12 +939,14 @@ static int bch2_fill_extent(struct bch_fs *c,
 		return fiemap_fill_next_extent(info,
 					       bkey_start_offset(k.k) << 9,
 					       0, k.k->size << 9,
+					       k.k->size << 9,
 					       flags|
 					       FIEMAP_EXTENT_DATA_INLINE);
 	} else if (k.k->type == KEY_TYPE_reservation) {
 		return fiemap_fill_next_extent(info,
 					       bkey_start_offset(k.k) << 9,
 					       0, k.k->size << 9,
+					       k.k->size << 9,
 					       flags|
 					       FIEMAP_EXTENT_DELALLOC|
 					       FIEMAP_EXTENT_UNWRITTEN);
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 7441245b1ceb..cdf662b9fb5b 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2743,7 +2743,7 @@ static int emit_last_fiemap_cache(struct fiemap_extent_info *fieinfo,
 		return 0;
 
 	ret = fiemap_fill_next_extent(fieinfo, cache->offset, cache->phys,
-				      cache->len, cache->flags);
+				      cache->len, cache->len, cache->flags);
 	cache->cached = false;
 	if (ret > 0)
 		ret = 0;
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index e57054bdc5fd..2b886e7189a5 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2215,6 +2215,7 @@ static int ext4_fill_es_cache_info(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 (next == 0)
 			break;
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index bd8674bf1d84..d68094753b84 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1843,7 +1843,8 @@ static int f2fs_xattr_fiemap(struct inode *inode,
 		if (!xnid)
 			flags |= FIEMAP_EXTENT_LAST;
 
-		err = fiemap_fill_next_extent(fieinfo, 0, phys, len, flags);
+		err = fiemap_fill_next_extent(
+				fieinfo, 0, phys, len, len, flags);
 		trace_f2fs_fiemap(inode, 0, phys, len, flags, err);
 		if (err)
 			return err;
@@ -1869,7 +1870,8 @@ static int f2fs_xattr_fiemap(struct inode *inode,
 	}
 
 	if (phys) {
-		err = fiemap_fill_next_extent(fieinfo, 0, phys, len, flags);
+		err = fiemap_fill_next_extent(
+				fieinfo, 0, phys, len, len, flags);
 		trace_f2fs_fiemap(inode, 0, phys, len, flags, err);
 	}
 
@@ -1988,7 +1990,7 @@ int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 			flags |= FIEMAP_EXTENT_DATA_ENCRYPTED;
 
 		ret = fiemap_fill_next_extent(fieinfo, logical,
-				phys, size, flags);
+				phys, size, size, flags);
 		trace_f2fs_fiemap(inode, logical, phys, size, flags, ret);
 		if (ret)
 			goto out;
diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c
index ac00423f117b..825b51978c56 100644
--- a/fs/f2fs/inline.c
+++ b/fs/f2fs/inline.c
@@ -806,7 +806,8 @@ int f2fs_inline_data_fiemap(struct inode *inode,
 	byteaddr = (__u64)ni.blk_addr << inode->i_sb->s_blocksize_bits;
 	byteaddr += (char *)inline_data_addr(inode, ipage) -
 					(char *)F2FS_INODE(ipage);
-	err = fiemap_fill_next_extent(fieinfo, start, byteaddr, ilen, flags);
+	err = fiemap_fill_next_extent(
+			fieinfo, start, byteaddr, ilen, ilen, flags);
 	trace_f2fs_fiemap(inode, start, byteaddr, ilen, flags, err);
 out:
 	f2fs_put_page(ipage, 1);
diff --git a/fs/ioctl.c b/fs/ioctl.c
index f8e5d6dfc62d..a5d0e7882f19 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -99,7 +99,8 @@ static int ioctl_fibmap(struct file *filp, int __user *p)
  * @fieinfo:	Fiemap context passed into ->fiemap
  * @logical:	Extent logical start offset, in bytes
  * @phys:	Extent physical start offset, in bytes
- * @len:	Extent length, in bytes
+ * @log_len:	Extent logical length, in bytes
+ * @phys_len:	Extent physical length, in bytes
  * @flags:	FIEMAP_EXTENT flags that describe this extent
  *
  * Called from file system ->fiemap callback. Will populate extent
@@ -110,7 +111,7 @@ static int ioctl_fibmap(struct file *filp, int __user *p)
  * extent that will fit in user array.
  */
 int fiemap_fill_next_extent(struct fiemap_extent_info *fieinfo, u64 logical,
-			    u64 phys, u64 len, u32 flags)
+			    u64 phys, u64 log_len, u64 phys_len, u32 flags)
 {
 	struct fiemap_extent extent;
 	struct fiemap_extent __user *dest = fieinfo->fi_extents_start;
@@ -138,8 +139,8 @@ int fiemap_fill_next_extent(struct fiemap_extent_info *fieinfo, u64 logical,
 	memset(&extent, 0, sizeof(extent));
 	extent.fe_logical = logical;
 	extent.fe_physical = phys;
-	extent.fe_length = len;
-	extent.fe_physical_length = len;
+	extent.fe_length = log_len;
+	extent.fe_physical_length = phys_len;
 	extent.fe_flags = flags;
 
 	dest += fieinfo->fi_extents_mapped;
diff --git a/fs/iomap/fiemap.c b/fs/iomap/fiemap.c
index 610ca6f1ec9b..30c5f14f908f 100644
--- a/fs/iomap/fiemap.c
+++ b/fs/iomap/fiemap.c
@@ -36,7 +36,7 @@ static int iomap_to_fiemap(struct fiemap_extent_info *fi,
 
 	return fiemap_fill_next_extent(fi, iomap->offset,
 			iomap->addr != IOMAP_NULL_ADDR ? iomap->addr : 0,
-			iomap->length, flags);
+			iomap->length, iomap->length, flags);
 }
 
 static loff_t iomap_fiemap_iter(const struct iomap_iter *iter,
diff --git a/fs/nilfs2/inode.c b/fs/nilfs2/inode.c
index a475095a5e80..e53a1b9ab393 100644
--- a/fs/nilfs2/inode.c
+++ b/fs/nilfs2/inode.c
@@ -1190,7 +1190,8 @@ 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;
 			}
@@ -1240,7 +1241,8 @@ 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;
@@ -1256,7 +1258,7 @@ 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/ntfs3/frecord.c b/fs/ntfs3/frecord.c
index 7f27382e0ce2..ba443e0b8d2b 100644
--- a/fs/ntfs3/frecord.c
+++ b/fs/ntfs3/frecord.c
@@ -1948,6 +1948,7 @@ int ni_fiemap(struct ntfs_inode *ni, struct fiemap_extent_info *fieinfo,
 		err = fiemap_fill_next_extent(
 			fieinfo, 0, 0,
 			attr ? le32_to_cpu(attr->res.data_size) : 0,
+			attr ? le32_to_cpu(attr->res.data_size) : 0,
 			FIEMAP_EXTENT_DATA_INLINE | FIEMAP_EXTENT_LAST |
 				FIEMAP_EXTENT_MERGED);
 		goto out;
@@ -2042,7 +2043,7 @@ int ni_fiemap(struct ntfs_inode *ni, struct fiemap_extent_info *fieinfo,
 				flags |= FIEMAP_EXTENT_LAST;
 
 			err = fiemap_fill_next_extent(fieinfo, vbo, lbo, dlen,
-						      flags);
+						      dlen, flags);
 			if (err < 0)
 				break;
 			if (err == 1) {
@@ -2062,7 +2063,8 @@ int ni_fiemap(struct ntfs_inode *ni, struct fiemap_extent_info *fieinfo,
 		if (vbo + bytes >= end)
 			flags |= FIEMAP_EXTENT_LAST;
 
-		err = fiemap_fill_next_extent(fieinfo, vbo, lbo, bytes, flags);
+		err = fiemap_fill_next_extent(fieinfo, vbo, lbo, bytes, bytes,
+					      flags);
 		if (err < 0)
 			break;
 		if (err == 1) {
diff --git a/fs/ocfs2/extent_map.c b/fs/ocfs2/extent_map.c
index 70a768b623cf..553b1695671d 100644
--- a/fs/ocfs2/extent_map.c
+++ b/fs/ocfs2/extent_map.c
@@ -723,7 +723,7 @@ 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;
 	}
@@ -794,7 +794,7 @@ 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/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index 6ee22d0dbc00..79c839964c41 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -3778,6 +3778,7 @@ static int smb3_fiemap(struct cifs_tcon *tcon,
 				le64_to_cpu(out_data[i].file_offset),
 				le64_to_cpu(out_data[i].file_offset),
 				le64_to_cpu(out_data[i].length),
+				le64_to_cpu(out_data[i].length),
 				flags);
 		if (rc < 0)
 			goto out;
diff --git a/include/linux/fiemap.h b/include/linux/fiemap.h
index c50882f19235..17a6c32cdf3f 100644
--- a/include/linux/fiemap.h
+++ b/include/linux/fiemap.h
@@ -16,6 +16,6 @@ struct fiemap_extent_info {
 int fiemap_prep(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		u64 start, u64 *len, u32 supported_flags);
 int fiemap_fill_next_extent(struct fiemap_extent_info *info, u64 logical,
-			    u64 phys, u64 len, u32 flags);
+			    u64 phys, u64 log_len, u64 phys_len, u32 flags);
 
 #endif /* _LINUX_FIEMAP_H 1 */
-- 
2.44.0

[PATCH 3/3] btrfs: fiemap: return extent physical size

[Sweet Tea Dorminy]

Now that fiemap allows returning extent physical size, make btrfs return
the appropriate extent's actual disk size.

Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
---
 fs/btrfs/extent_io.c | 63 +++++++++++++++++++++++++++-----------------
 1 file changed, 39 insertions(+), 24 deletions(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index cdf662b9fb5b..4374c531e088 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2456,7 +2456,8 @@ int try_release_extent_mapping(struct page *page, gfp_t mask)
 struct btrfs_fiemap_entry {
 	u64 offset;
 	u64 phys;
-	u64 len;
+	u64 log_len;
+	u64 phys_len;
 	u32 flags;
 };
 
@@ -2514,7 +2515,8 @@ struct fiemap_cache {
 	/* Fields for the cached extent (unsubmitted, not ready, extent). */
 	u64 offset;
 	u64 phys;
-	u64 len;
+	u64 log_len;
+	u64 phys_len;
 	u32 flags;
 	bool cached;
 };
@@ -2527,8 +2529,8 @@ static int flush_fiemap_cache(struct fiemap_extent_info *fieinfo,
 		int ret;
 
 		ret = fiemap_fill_next_extent(fieinfo, entry->offset,
-					      entry->phys, entry->len,
-					      entry->flags);
+					      entry->phys, entry->log_len,
+					      entry->phys_len, entry->flags);
 		/*
 		 * Ignore 1 (reached max entries) because we keep track of that
 		 * ourselves in emit_fiemap_extent().
@@ -2553,7 +2555,8 @@ static int flush_fiemap_cache(struct fiemap_extent_info *fieinfo,
  */
 static int emit_fiemap_extent(struct fiemap_extent_info *fieinfo,
 				struct fiemap_cache *cache,
-				u64 offset, u64 phys, u64 len, u32 flags)
+				u64 offset, u64 phys, u64 log_len,
+				u64 phys_len, u32 flags)
 {
 	struct btrfs_fiemap_entry *entry;
 	u64 cache_end;
@@ -2596,7 +2599,7 @@ static int emit_fiemap_extent(struct fiemap_extent_info *fieinfo,
 	 * or equals to what we have in cache->offset. We deal with this as
 	 * described below.
 	 */
-	cache_end = cache->offset + cache->len;
+	cache_end = cache->offset + cache->log_len;
 	if (cache_end > offset) {
 		if (offset == cache->offset) {
 			/*
@@ -2620,10 +2623,10 @@ static int emit_fiemap_extent(struct fiemap_extent_info *fieinfo,
 			 * where a previously found file extent item was split
 			 * due to an ordered extent completing.
 			 */
-			cache->len = offset - cache->offset;
+			cache->log_len = offset - cache->offset;
 			goto emit;
 		} else {
-			const u64 range_end = offset + len;
+			const u64 range_end = offset + log_len;
 
 			/*
 			 * The offset of the file extent item we have just found
@@ -2660,7 +2663,7 @@ static int emit_fiemap_extent(struct fiemap_extent_info *fieinfo,
 				phys += cache_end - offset;
 
 			offset = cache_end;
-			len = range_end - cache_end;
+			log_len = range_end - cache_end;
 			goto emit;
 		}
 	}
@@ -2670,15 +2673,17 @@ static int emit_fiemap_extent(struct fiemap_extent_info *fieinfo,
 	 * 1) Their logical addresses are continuous
 	 *
 	 * 2) Their physical addresses are continuous
-	 *    So truly compressed (physical size smaller than logical size)
-	 *    extents won't get merged with each other
 	 *
 	 * 3) Share same flags
+	 *
+	 * 4) Not compressed
 	 */
-	if (cache->offset + cache->len  == offset &&
-	    cache->phys + cache->len == phys  &&
-	    cache->flags == flags) {
-		cache->len += len;
+	if (cache->offset + cache->log_len  == offset &&
+	    cache->phys + cache->log_len == phys  &&
+	    cache->flags == flags &&
+	    !(flags & FIEMAP_EXTENT_ENCODED)) {
+		cache->log_len += log_len;
+		cache->phys_len += phys_len;
 		return 0;
 	}
 
@@ -2695,7 +2700,7 @@ static int emit_fiemap_extent(struct fiemap_extent_info *fieinfo,
 		 * to miss it.
 		 */
 		entry = &cache->entries[cache->entries_size - 1];
-		cache->next_search_offset = entry->offset + entry->len;
+		cache->next_search_offset = entry->offset + entry->log_len;
 		cache->cached = false;
 
 		return BTRFS_FIEMAP_FLUSH_CACHE;
@@ -2704,7 +2709,8 @@ static int emit_fiemap_extent(struct fiemap_extent_info *fieinfo,
 	entry = &cache->entries[cache->entries_pos];
 	entry->offset = cache->offset;
 	entry->phys = cache->phys;
-	entry->len = cache->len;
+	entry->log_len = cache->log_len;
+	entry->phys_len = cache->phys_len;
 	entry->flags = cache->flags;
 	cache->entries_pos++;
 	cache->extents_mapped++;
@@ -2717,7 +2723,8 @@ static int emit_fiemap_extent(struct fiemap_extent_info *fieinfo,
 	cache->cached = true;
 	cache->offset = offset;
 	cache->phys = phys;
-	cache->len = len;
+	cache->log_len = log_len;
+	cache->phys_len = phys_len;
 	cache->flags = flags;
 
 	return 0;
@@ -2743,7 +2750,8 @@ static int emit_last_fiemap_cache(struct fiemap_extent_info *fieinfo,
 		return 0;
 
 	ret = fiemap_fill_next_extent(fieinfo, cache->offset, cache->phys,
-				      cache->len, cache->len, cache->flags);
+				      cache->log_len, cache->phys_len,
+				      cache->flags);
 	cache->cached = false;
 	if (ret > 0)
 		ret = 0;
@@ -2937,13 +2945,15 @@ static int fiemap_process_hole(struct btrfs_inode *inode,
 			}
 			ret = emit_fiemap_extent(fieinfo, cache, prealloc_start,
 						 disk_bytenr + extent_offset,
-						 prealloc_len, prealloc_flags);
+						 prealloc_len, prealloc_len,
+						 prealloc_flags);
 			if (ret)
 				return ret;
 			extent_offset += prealloc_len;
 		}
 
 		ret = emit_fiemap_extent(fieinfo, cache, delalloc_start, 0,
+					 delalloc_end + 1 - delalloc_start,
 					 delalloc_end + 1 - delalloc_start,
 					 FIEMAP_EXTENT_DELALLOC |
 					 FIEMAP_EXTENT_UNKNOWN);
@@ -2984,7 +2994,8 @@ static int fiemap_process_hole(struct btrfs_inode *inode,
 		}
 		ret = emit_fiemap_extent(fieinfo, cache, prealloc_start,
 					 disk_bytenr + extent_offset,
-					 prealloc_len, prealloc_flags);
+					 prealloc_len, prealloc_len,
+					 prealloc_flags);
 		if (ret)
 			return ret;
 	}
@@ -3130,6 +3141,7 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo,
 		u64 extent_offset = 0;
 		u64 extent_gen;
 		u64 disk_bytenr = 0;
+		u64 disk_size = 0;
 		u64 flags = 0;
 		int extent_type;
 		u8 compression;
@@ -3192,7 +3204,7 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo,
 			flags |= FIEMAP_EXTENT_DATA_INLINE;
 			flags |= FIEMAP_EXTENT_NOT_ALIGNED;
 			ret = emit_fiemap_extent(fieinfo, &cache, key.offset, 0,
-						 extent_len, flags);
+						 extent_len, extent_len, flags);
 		} else if (extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
 			ret = fiemap_process_hole(inode, fieinfo, &cache,
 						  &delalloc_cached_state,
@@ -3207,6 +3219,7 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo,
 						  backref_ctx, 0, 0, 0,
 						  key.offset, extent_end - 1);
 		} else {
+			disk_size = btrfs_file_extent_disk_num_bytes(leaf, ei);
 			/* We have a regular extent. */
 			if (fieinfo->fi_extents_max) {
 				ret = btrfs_is_data_extent_shared(inode,
@@ -3221,7 +3234,9 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo,
 
 			ret = emit_fiemap_extent(fieinfo, &cache, key.offset,
 						 disk_bytenr + extent_offset,
-						 extent_len, flags);
+						 extent_len,
+						 disk_size - extent_offset,
+						 flags);
 		}
 
 		if (ret < 0) {
@@ -3259,7 +3274,7 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo,
 		prev_extent_end = range_end;
 	}
 
-	if (cache.cached && cache.offset + cache.len >= last_extent_end) {
+	if (cache.cached && cache.offset + cache.log_len >= last_extent_end) {
 		const u64 i_size = i_size_read(&inode->vfs_inode);
 
 		if (prev_extent_end < i_size) {
-- 
2.44.0

Re: [PATCH 1/3] add physical_length field to fiemap extents

[Andreas Dilger]

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On Mar 8, 2024, at 11:03 AM, Sweet Tea Dorminy <sweettea-kernel@dorminy.me> wrote:
> 
> Some filesystems support compressed extents which have a larger logical
> size than physical, and for those filesystems, it can be useful for
> userspace to know how much space those extents actually use. For
> instance, the compsize [1] tool for btrfs currently uses btrfs-internal,
> root-only ioctl to find the actual disk space used by a file; it would
> be better and more useful for this information to require fewer
> privileges and to be usable on more filesystems. Therefore, use one of
> the padding u64s in the fiemap extent structure to return the actual
> physical length; and, for now, return this as equal to the logical
> length.

Thank you for working on this patch.  Note that there was a patch from
David Sterba and a lengthy discussion about exactly this functionality
several years ago.  If you haven't already read the details, it would be
useful to do so. I think the thread had mostly come to good conclusions,
but the patch never made it into the kernel.

https://patchwork.ozlabs.org/project/linux-ext4/patch/4f8d5dc5b51a43efaf16c39398c23a6276e40a30.1386778303.git.dsterba@suse.cz/

One of those conclusions was that the kernel should always fill in the
fe_physical_length field in the returned extent, and set a flag:

#define FIEMAP_EXTENT_PHYS_LENGTH      0x00000010

to indicate to userspace that the physical length field is valid.

There should also be a separate flag for extents that are compressed:

#define FIEMAP_EXTENT_DATA_COMPRESSED  0x00000040

Rename fe_length to fe_logical_length and #define fe_length fe_logical_length
so that it is more clear which field is which in the data structure, but
does not break compatibility.

I think this patch gets most of this right, except the presence of the
flags to indicate the PHYS_LENGTH and DATA_COMPRESSED state in the extent.

Cheers, Andreas

> [1] https://github.com/kilobyte/compsize
> 
> Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
> ---
> Documentation/filesystems/fiemap.rst | 26 ++++++++++++++++++--------
> fs/ioctl.c                           |  1 +
> include/uapi/linux/fiemap.h          | 24 +++++++++++++++++-------
> 3 files changed, 36 insertions(+), 15 deletions(-)
> 
> diff --git a/Documentation/filesystems/fiemap.rst b/Documentation/filesystems/fiemap.rst
> index 93fc96f760aa..e3e84573b087 100644
> --- a/Documentation/filesystems/fiemap.rst
> +++ b/Documentation/filesystems/fiemap.rst
> @@ -80,14 +80,24 @@ Each extent is described by a single fiemap_extent structure as
> returned in fm_extents::
> 
>     struct fiemap_extent {
> -	    __u64	fe_logical;  /* logical offset in bytes for the start of
> -				* the extent */
> -	    __u64	fe_physical; /* physical offset in bytes for the start
> -				* of the extent */
> -	    __u64	fe_length;   /* length in bytes for the extent */
> -	    __u64	fe_reserved64[2];
> -	    __u32	fe_flags;    /* FIEMAP_EXTENT_* flags for this extent */
> -	    __u32	fe_reserved[3];
> +            /*
> +             * logical offset in bytes for the start of
> +             * the extent from the beginning of the file
> +             */
> +            __u64 fe_logical;
> +            /*
> +             * physical offset in bytes for the start
> +             * of the extent from the beginning of the disk
> +             */
> +            __u64 fe_physical;
> +            /* length in bytes for this extent */
> +            __u64 fe_length;
> +            /* physical length in bytes for this extent */
> +            __u64 fe_physical_length;
> +            __u64 fe_reserved64[1];
> +            /* FIEMAP_EXTENT_* flags for this extent */
> +            __u32 fe_flags;
> +            __u32 fe_reserved[3];
>     };
> 
> All offsets and lengths are in bytes and mirror those on disk.  It is valid
> diff --git a/fs/ioctl.c b/fs/ioctl.c
> index 1d5abfdf0f22..f8e5d6dfc62d 100644
> --- a/fs/ioctl.c
> +++ b/fs/ioctl.c
> @@ -139,6 +139,7 @@ int fiemap_fill_next_extent(struct fiemap_extent_info *fieinfo, u64 logical,
> 	extent.fe_logical = logical;
> 	extent.fe_physical = phys;
> 	extent.fe_length = len;
> +	extent.fe_physical_length = len;
> 	extent.fe_flags = flags;
> 
> 	dest += fieinfo->fi_extents_mapped;
> diff --git a/include/uapi/linux/fiemap.h b/include/uapi/linux/fiemap.h
> index 24ca0c00cae3..fd3c7d380666 100644
> --- a/include/uapi/linux/fiemap.h
> +++ b/include/uapi/linux/fiemap.h
> @@ -15,13 +15,23 @@
> #include <linux/types.h>
> 
> struct fiemap_extent {
> -	__u64 fe_logical;  /* logical offset in bytes for the start of
> -			    * the extent from the beginning of the file */
> -	__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];
> -	__u32 fe_flags;    /* FIEMAP_EXTENT_* flags for this extent */
> +	/*
> +	 * logical offset in bytes for the start of
> +	 * the extent from the beginning of the file
> +	 */
> +	__u64 fe_logical;
> +	/*
> +	 * physical offset in bytes for the start
> +	 * of the extent from the beginning of the disk
> +	 */
> +	__u64 fe_physical;
> +	/* length in bytes for this extent */
> +	__u64 fe_length;
> +	/* physical length in bytes for this extent */
> +	__u64 fe_physical_length;
> +	__u64 fe_reserved64[1];
> +	/* FIEMAP_EXTENT_* flags for this extent */
> +	__u32 fe_flags;
> 	__u32 fe_reserved[3];
> };
> 
> --
> 2.44.0
> 
> 


Cheers, Andreas






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Re: [PATCH 1/3] add physical_length field to fiemap extents

[Eric Biggers]

On Mon, Mar 11, 2024 at 06:22:02PM -0600, Andreas Dilger wrote:
> On Mar 8, 2024, at 11:03 AM, Sweet Tea Dorminy <sweettea-kernel@dorminy.me> wrote:
> > 
> > Some filesystems support compressed extents which have a larger logical
> > size than physical, and for those filesystems, it can be useful for
> > userspace to know how much space those extents actually use. For
> > instance, the compsize [1] tool for btrfs currently uses btrfs-internal,
> > root-only ioctl to find the actual disk space used by a file; it would
> > be better and more useful for this information to require fewer
> > privileges and to be usable on more filesystems. Therefore, use one of
> > the padding u64s in the fiemap extent structure to return the actual
> > physical length; and, for now, return this as equal to the logical
> > length.
> 
> Thank you for working on this patch.  Note that there was a patch from
> David Sterba and a lengthy discussion about exactly this functionality
> several years ago.  If you haven't already read the details, it would be
> useful to do so. I think the thread had mostly come to good conclusions,
> but the patch never made it into the kernel.
> 
> https://patchwork.ozlabs.org/project/linux-ext4/patch/4f8d5dc5b51a43efaf16c39398c23a6276e40a30.1386778303.git.dsterba@suse.cz/
> 
> One of those conclusions was that the kernel should always fill in the
> fe_physical_length field in the returned extent, and set a flag:
> 
> #define FIEMAP_EXTENT_PHYS_LENGTH      0x00000010
> 
> to indicate to userspace that the physical length field is valid.
> 
> There should also be a separate flag for extents that are compressed:
> 
> #define FIEMAP_EXTENT_DATA_COMPRESSED  0x00000040
> 
> Rename fe_length to fe_logical_length and #define fe_length fe_logical_length
> so that it is more clear which field is which in the data structure, but
> does not break compatibility.
> 
> I think this patch gets most of this right, except the presence of the
> flags to indicate the PHYS_LENGTH and DATA_COMPRESSED state in the extent.
> 
> Cheers, Andreas

Thanks for resurrecting this.  Andreas's suggestions sound good to me.  And yes,
please try to search for any past discussions on this topic.

It may be a good idea to Cc the f2fs mailing list
(linux-f2fs-devel@lists.sourceforge.net), since this will be useful for f2fs
too, since f2fs supports compression.

One use case is that this will make testing the combination of
compression+encryption (e.g. as xfstest f2fs/002 tries to do) easier.

- Eric

Re: [PATCH 1/3] add physical_length field to fiemap extents

[Sweet Tea Dorminy]

On 2024-03-11 20:22, Andreas Dilger wrote:
> On Mar 8, 2024, at 11:03 AM, Sweet Tea Dorminy
> <sweettea-kernel@dorminy.me> wrote:
>> 
>> Some filesystems support compressed extents which have a larger 
>> logical
>> size than physical, and for those filesystems, it can be useful for
>> userspace to know how much space those extents actually use. For
>> instance, the compsize [1] tool for btrfs currently uses 
>> btrfs-internal,
>> root-only ioctl to find the actual disk space used by a file; it would
>> be better and more useful for this information to require fewer
>> privileges and to be usable on more filesystems. Therefore, use one of
>> the padding u64s in the fiemap extent structure to return the actual
>> physical length; and, for now, return this as equal to the logical
>> length.
> 
> Thank you for working on this patch.  Note that there was a patch from
> David Sterba and a lengthy discussion about exactly this functionality
> several years ago.  If you haven't already read the details, it would 
> be
> useful to do so. I think the thread had mostly come to good 
> conclusions,
> but the patch never made it into the kernel.
> 
> https://patchwork.ozlabs.org/project/linux-ext4/patch/4f8d5dc5b51a43efaf16c39398c23a6276e40a30.1386778303.git.dsterba@suse.cz/
> 
> One of those conclusions was that the kernel should always fill in the
> fe_physical_length field in the returned extent, and set a flag:
> 
> #define FIEMAP_EXTENT_PHYS_LENGTH      0x00000010
> 
> to indicate to userspace that the physical length field is valid.
> 
> There should also be a separate flag for extents that are compressed:
> 
> #define FIEMAP_EXTENT_DATA_COMPRESSED  0x00000040
> 
> Rename fe_length to fe_logical_length and #define fe_length 
> fe_logical_length
> so that it is more clear which field is which in the data structure, 
> but
> does not break compatibility.
> 
> I think this patch gets most of this right, except the presence of the
> flags to indicate the PHYS_LENGTH and DATA_COMPRESSED state in the 
> extent.
> 
> Cheers, Andreas
> 
I had not seen that; thank you for the pointers, I'll add the flags in 
v2.

Re: [PATCH 0/3] fiemap extension to add physical extent length

[Darrick J. Wong]

On Fri, Mar 08, 2024 at 01:03:17PM -0500, Sweet Tea Dorminy wrote:
> For many years, various btrfs users have written programs to discover
> the actual disk space used by files, using root-only interfaces.
> However, this information is a great fit for fiemap: it is inherently
> tied to extent information, all filesystems can use it, and the
> capabilities required for FIEMAP make sense for this additional
> information also.
> 
> Hence, this patchset adds physical extent length information to fiemap,
> and extends btrfs to return it.  This uses some of the reserved padding
> in the fiemap extent structure, so programs unaware of the new field
> will be unaffected by its presence.
> 
> This is based on next-20240307. I've tested the btrfs part of this with
> the standard btrfs testing matrix locally, and verified that the physical extent
> information returned there is correct, but I'm still waiting on more
> tests. Please let me know what you think of the general idea!

Seems useful!  Any chance you'd be willing to pick up this old proposal
to report the dev_t through iomap?  iirc the iomap wrappers for fiemap
can export that pretty easily.

https://lore.kernel.org/linux-fsdevel/20190211094306.fjr6gfehcstm7eqq@hades.usersys.redhat.com/

(Not sure what we do for pmem filesystems)

--D

> Sweet Tea Dorminy (3):
>   fs: add physical_length field to fiemap extents
>   fs: update fiemap_fill_next_extent() signature
>   btrfs: fiemap: return extent physical size
> 
>  Documentation/filesystems/fiemap.rst | 29 +++++++++----
>  fs/bcachefs/fs.c                     |  6 ++-
>  fs/btrfs/extent_io.c                 | 63 +++++++++++++++++-----------
>  fs/ext4/extents.c                    |  1 +
>  fs/f2fs/data.c                       |  8 ++--
>  fs/f2fs/inline.c                     |  3 +-
>  fs/ioctl.c                           |  8 ++--
>  fs/iomap/fiemap.c                    |  2 +-
>  fs/nilfs2/inode.c                    |  8 ++--
>  fs/ntfs3/frecord.c                   |  6 ++-
>  fs/ocfs2/extent_map.c                |  4 +-
>  fs/smb/client/smb2ops.c              |  1 +
>  include/linux/fiemap.h               |  2 +-
>  include/uapi/linux/fiemap.h          | 24 +++++++----
>  14 files changed, 108 insertions(+), 57 deletions(-)
> 
> 
> base-commit: 1843e16d2df9d98427ef8045589571749d627cf7
> -- 
> 2.44.0
> 
> 

Re: [PATCH 0/3] fiemap extension to add physical extent length

[David Sterba]

On Thu, Mar 14, 2024 at 08:03:34PM -0700, Darrick J. Wong wrote:
> On Fri, Mar 08, 2024 at 01:03:17PM -0500, Sweet Tea Dorminy wrote:
> > For many years, various btrfs users have written programs to discover
> > the actual disk space used by files, using root-only interfaces.
> > However, this information is a great fit for fiemap: it is inherently
> > tied to extent information, all filesystems can use it, and the
> > capabilities required for FIEMAP make sense for this additional
> > information also.
> > 
> > Hence, this patchset adds physical extent length information to fiemap,
> > and extends btrfs to return it.  This uses some of the reserved padding
> > in the fiemap extent structure, so programs unaware of the new field
> > will be unaffected by its presence.
> > 
> > This is based on next-20240307. I've tested the btrfs part of this with
> > the standard btrfs testing matrix locally, and verified that the physical extent
> > information returned there is correct, but I'm still waiting on more
> > tests. Please let me know what you think of the general idea!
> 
> Seems useful!  Any chance you'd be willing to pick up this old proposal
> to report the dev_t through iomap?  iirc the iomap wrappers for fiemap
> can export that pretty easily.
> 
> https://lore.kernel.org/linux-fsdevel/20190211094306.fjr6gfehcstm7eqq@hades.usersys.redhat.com/

I think this is not too useful for btrfs (in general) due to the block
group profiles that store copies on multiple devices, we'd need more
than one device identifier per extent.

Re: [PATCH 0/3] fiemap extension to add physical extent length

[Andreas Dilger]

[-- Attachment #1: Type: text/plain, Size: 2331 bytes --]

On Mar 21, 2024, at 12:58 PM, David Sterba <dsterba@suse.cz> wrote:
> 
> On Thu, Mar 14, 2024 at 08:03:34PM -0700, Darrick J. Wong wrote:
>> On Fri, Mar 08, 2024 at 01:03:17PM -0500, Sweet Tea Dorminy wrote:
>>> For many years, various btrfs users have written programs to discover
>>> the actual disk space used by files, using root-only interfaces.
>>> However, this information is a great fit for fiemap: it is inherently
>>> tied to extent information, all filesystems can use it, and the
>>> capabilities required for FIEMAP make sense for this additional
>>> information also.
>>> 
>>> Hence, this patchset adds physical extent length information to fiemap,
>>> and extends btrfs to return it.  This uses some of the reserved padding
>>> in the fiemap extent structure, so programs unaware of the new field
>>> will be unaffected by its presence.
>>> 
>>> This is based on next-20240307. I've tested the btrfs part of this with
>>> the standard btrfs testing matrix locally, and verified that the physical extent
>>> information returned there is correct, but I'm still waiting on more
>>> tests. Please let me know what you think of the general idea!
>> 
>> Seems useful!  Any chance you'd be willing to pick up this old proposal
>> to report the dev_t through iomap?  iirc the iomap wrappers for fiemap
>> can export that pretty easily.
>> 
>> https://lore.kernel.org/linux-fsdevel/20190211094306.fjr6gfehcstm7eqq@hades.usersys.redhat.com/
> 
> I think this is not too useful for btrfs (in general) due to the block
> group profiles that store copies on multiple devices, we'd need more
> than one device identifier per extent.

My thought would be that there are multiple overlapping extents with the
same logical offset returned in this case.  It wouldn't just be the device
that would be different in this case, but also the physical offset may be
different on each device (depending on how allocation is done), and maybe
even the length and flags are different if one device stores compressed
data and another one does not.

Having multiple overlapping extents for files with built-in mirrors allows
freedom for all of the extent parameters to be different, doesn't have any
limits on the number of copies/devices that could fit in one extent, etc.

Cheers, Andreas






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