e2fsprogs: let debugfs do sparse copy

Let debugfs do sparse copy when src is a sparse file, just like
"cp --sparse=auto"

This patch has been reviewed by the linux-ext4 mailing list, but isn't
merged atm.

[YOCTO #3848]

(From OE-Core rev: 723adaf8fbba61b7f1adc8e4a13ddf1cfb5c0bcf)

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/e2fsprogs/e2fsprogs-1.42.8/debugfs-sparse-copy.patch

@@ -0,0 +1,148 @@
+debugfs.c: do sparse copy when src is a sparse file
+
+Let debugfs do sparse copy when src is a sparse file, just like
+"cp --sparse=auto"
+
+* For the:
+  #define IO_BUFSIZE 64*1024
+  this is a suggested value from gnu coreutils:
+  http://git.savannah.gnu.org/gitweb/?p=coreutils.git;a=blob;f=src/ioblksize.h;h=1ae93255e7d0ccf0855208c7ae5888209997bf16;hb=HEAD
+
+* Use malloc() to allocate memory for the buffer since put 64K (or
+  more) on the stack seems not a good idea.
+
+Upstream-Status: Submitted
+
+Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
+Acked-by: Darren Hart <dvhart@linux.intel.com>
+---
+ debugfs/debugfs.c |   62 +++++++++++++++++++++++++++++++++++++++++++++++++----
+ 1 file changed, 58 insertions(+), 4 deletions(-)
+
+diff --git a/debugfs/debugfs.c b/debugfs/debugfs.c
+--- a/debugfs/debugfs.c
++++ b/debugfs/debugfs.c
+@@ -41,6 +41,16 @@ extern char *optarg;
+ #define BUFSIZ 8192
+ #endif
+ 
++/* 64KiB is the minimium blksize to best minimize system call overhead. */
++#ifndef IO_BUFSIZE
++#define IO_BUFSIZE 64*1024
++#endif
++
++/* Block size for `st_blocks' */
++#ifndef S_BLKSIZE
++#define S_BLKSIZE 512
++#endif
++
+ ss_request_table *extra_cmds;
+ const char *debug_prog_name;
+ int sci_idx;
+@@ -1563,22 +1573,37 @@ void do_find_free_inode(int argc, char *argv[])
+ }
+ 
+ #ifndef READ_ONLY
+-static errcode_t copy_file(int fd, ext2_ino_t newfile)
++static errcode_t copy_file(int fd, ext2_ino_t newfile, int bufsize, int make_holes)
+ {
+ 	ext2_file_t	e2_file;
+ 	errcode_t	retval;
+ 	int		got;
+ 	unsigned int	written;
+-	char		buf[8192];
++	char		*buf;
+ 	char		*ptr;
++	char		*zero_buf;
++	int		cmp;
+ 
+ 	retval = ext2fs_file_open(current_fs, newfile,
+ 				  EXT2_FILE_WRITE, &e2_file);
+ 	if (retval)
+ 		return retval;
+ 
++	if (!(buf = (char *) malloc(bufsize))){
++		com_err("copy_file", errno, "can't allocate buffer\n");
++		return;
++	}
++
++	/* This is used for checking whether the whole block is zero */
++	retval = ext2fs_get_memzero(bufsize, &zero_buf);
++	if (retval) {
++		com_err("copy_file", retval, "can't allocate buffer\n");
++		free(buf);
++		return retval;
++	}
++
+ 	while (1) {
+-		got = read(fd, buf, sizeof(buf));
++		got = read(fd, buf, bufsize);
+ 		if (got == 0)
+ 			break;
+ 		if (got < 0) {
+@@ -1586,6 +1611,21 @@ static errcode_t copy_file(int fd, ext2_ino_t newfile)
+ 			goto fail;
+ 		}
+ 		ptr = buf;
++
++		/* Sparse copy */
++		if (make_holes) {
++			/* Check whether all is zero */
++			cmp = memcmp(ptr, zero_buf, got);
++			if (cmp == 0) {
++				 /* The whole block is zero, make a hole */
++				retval = ext2fs_file_lseek(e2_file, got, EXT2_SEEK_CUR, NULL);
++				if (retval)
++					goto fail;
++				got = 0;
++			}
++		}
++
++		/* Normal copy */
+ 		while (got > 0) {
+ 			retval = ext2fs_file_write(e2_file, ptr,
+ 						   got, &written);
+@@ -1596,10 +1636,14 @@ static errcode_t copy_file(int fd, ext2_ino_t newfile)
+ 			ptr += written;
+ 		}
+ 	}
++	free(buf);
++	ext2fs_free_mem(&zero_buf);
+ 	retval = ext2fs_file_close(e2_file);
+ 	return retval;
+ 
+ fail:
++	free(buf);
++	ext2fs_free_mem(&zero_buf);
+ 	(void) ext2fs_file_close(e2_file);
+ 	return retval;
+ }
+@@ -1612,6 +1656,8 @@ void do_write(int argc, char *argv[])
+ 	ext2_ino_t	newfile;
+ 	errcode_t	retval;
+ 	struct ext2_inode inode;
++	int		bufsize = IO_BUFSIZE;
++	int		make_holes = 0;
+ 
+ 	if (common_args_process(argc, argv, 3, 3, "write",
+ 				"<native file> <new file>", CHECK_FS_RW))
+@@ -1687,7 +1733,15 @@ void do_write(int argc, char *argv[])
+ 		return;
+ 	}
+ 	if (LINUX_S_ISREG(inode.i_mode)) {
+-		retval = copy_file(fd, newfile);
++		if (statbuf.st_blocks < statbuf.st_size / S_BLKSIZE) {
++			make_holes = 1;
++			/*
++			 * Use I/O blocksize as buffer size when
++			 * copying sparse files.
++			 */
++			bufsize = statbuf.st_blksize;
++		}
++		retval = copy_file(fd, newfile, bufsize, make_holes);
+ 		if (retval)
+ 			com_err("copy_file", retval, 0);
+ 	}
+-- 
+1.7.10.4
+

meta/recipes-devtools/e2fsprogs/e2fsprogs_1.42.8.bb

@@ -4,6 +4,7 @@ require e2fsprogs.inc
 SRC_URI += "file://acinclude.m4 \
             file://remove.ldconfig.call.patch \
             file://debugfs-too-short.patch \
+            file://debugfs-sparse-copy.patch \
 "
 
 SRC_URI[md5sum] = "8ef664b6eb698aa6b733df59b17b9ed4"