Let debugfs do sparse copy when src is a sparse file, just like
"cp --sparse=auto"
* For the
#define IO_BUFSIZE 32*1024
This is from coreutils-8.13/src/ioblksize.h (GPL V3):
/* As of Mar 2009, 32KiB is determined to be the minimium
blksize to best minimize system call overhead.
This can be tested with this script with the results
shown for a 1.7GHz pentium-m with 2GB of 400MHz DDR2 RAM:
for i in $(seq 0 10); do
size=$((8*1024**3)) #ensure this is big enough
bs=$((1024*2**$i))
printf "%7s=" $bs
dd bs=$bs if=/dev/zero of=/dev/null count=$(($size/$bs)) 2>&1 |
sed -n 's/.* \([0-9.]* [GM]B\/s\)/\1/p'
done
1024=734 MB/s
2048=1.3 GB/s
4096=2.4 GB/s
8192=3.5 GB/s
16384=3.9 GB/s
32768=5.2 GB/s
65536=5.3 GB/s
131072=5.5 GB/s
262144=5.7 GB/s
524288=5.7 GB/s
1048576=5.8 GB/s
Note that this is to minimize system call overhead.
Other values may be appropriate to minimize file system
or disk overhead. For example on my current GNU/Linux system
the readahead setting is 128KiB which was read using:
file="."
device=$(df -P --local "$file" | tail -n1 | cut -d' ' -f1)
echo $(( $(blockdev --getra $device) * 512 ))
However there isn't a portable way to get the above.
In the future we could use the above method if available
and default to io_blksize() if not.
*/
enum { IO_BUFSIZE = 32*1024 };
Signed-off-by: Robert Yang <liezhi.yang@xxxxxxxxxxxxx>
Acked-by: Darren Hart <dvhart@xxxxxxxxxxxxxxx>
---
debugfs/debugfs.c | 70 +++++++++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 60 insertions(+), 10 deletions(-)
diff --git a/debugfs/debugfs.c b/debugfs/debugfs.c
index b77d0b5..e443703 100644
--- a/debugfs/debugfs.c
+++ b/debugfs/debugfs.c
@@ -37,6 +37,16 @@ extern char *optarg;
#include "../version.h"
#include "jfs_user.h"
+/* 32KiB is the minimium blksize to best minimize system call overhead. */
+#ifndef IO_BUFSIZE
+#define IO_BUFSIZE 32*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;
@@ -1571,14 +1581,17 @@ 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, int *zero_written)
{
ext2_file_t e2_file;
errcode_t retval;
int got;
unsigned int written;
- char buf[8192];
+ char buf[bufsize];
char *ptr;
+ char *cp;
+ int count;
retval = ext2fs_file_open(current_fs, newfile,
EXT2_FILE_WRITE, &e2_file);
@@ -1594,14 +1607,30 @@ static errcode_t copy_file(int fd, ext2_ino_t newfile)
goto fail;
}
ptr = buf;
+ cp = ptr;
+ count = got;
while (got > 0) {
- retval = ext2fs_file_write(e2_file, ptr,
- got, &written);
- if (retval)
- goto fail;
-
- got -= written;
- ptr += written;
+ if (make_holes) {
+ /* Check whether all is zero */
+ while (count-- && *cp++ == 0)
+ continue;
+ if (count < 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 */
+ if (got > 0) {
+ *zero_written = 0;
+ retval = ext2fs_file_write(e2_file, ptr, got, &written);
+ if (retval)
+ goto fail;
+ got -= written;
+ ptr += written;
+ }
}
}
retval = ext2fs_file_close(e2_file);
@@ -1620,6 +1649,9 @@ 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;
+ int zero_written = 1;
if (common_args_process(argc, argv, 3, 3, "write",
"<native file> <new file>", CHECK_FS_RW))
@@ -1684,9 +1716,27 @@ 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, &zero_written);
if (retval)
com_err("copy_file", retval, 0);
+
+ if ((inode.i_flags & EXT4_EXTENTS_FL) && zero_written) {
+ /*
+ * If no data is copied which indicateds that no write
+ * happens, we need to turn off the EXT4_EXTENTS_FL.
+ */
+ inode.i_flags &= ~EXT4_EXTENTS_FL;
+ if (debugfs_write_inode(newfile, &inode, argv[0]))
+ close(fd);
+ }
}
close(fd);
}
--
1.8.1.2
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