Patchwork [2/2] debugfs.c: do sparse copy when src is a sparse file

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Submitter Robert Yang
Date July 26, 2013, 10:30 a.m.
Message ID <1374834657-17091-3-git-send-email-liezhi.yang@windriver.com>
Download mbox | patch
Permalink /patch/262119/
State Superseded
Headers show

Comments

Robert Yang - July 26, 2013, 10:30 a.m.
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.

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Acked-by: Darren Hart <dvhart@linux.intel.com>
---
 debugfs/debugfs.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 53 insertions(+), 5 deletions(-)
Darrick J. Wong - July 26, 2013, 4:02 p.m.
On Fri, Jul 26, 2013 at 06:30:57PM +0800, Robert Yang wrote:
> 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.
> 
> Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
> Acked-by: Darren Hart <dvhart@linux.intel.com>
> ---
>  debugfs/debugfs.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++-----
>  1 file changed, 53 insertions(+), 5 deletions(-)
> 
> diff --git a/debugfs/debugfs.c b/debugfs/debugfs.c
> index b77d0b5..0379f38 100644
> --- a/debugfs/debugfs.c
> +++ b/debugfs/debugfs.c
> @@ -37,6 +37,16 @@ extern char *optarg;
>  #include "../version.h"
>  #include "jfs_user.h"
>  
> +/* 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;
> @@ -1571,22 +1581,28 @@ 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		*zeromem;
> +	int		cmp;
>  
>  	retval = ext2fs_file_open(current_fs, newfile,
>  				  EXT2_FILE_WRITE, &e2_file);
>  	if (retval)
>  		return retval;
>  
> +	if (!(buf = (char *) malloc(bufsize))){
> +		fprintf(stderr, "copy_file: can't allocate buffer\n");
> +		return;
> +	}
>  	while (1) {
> -		got = read(fd, buf, sizeof(buf));
> +		got = read(fd, buf, bufsize);
>  		if (got == 0)
>  			break;
>  		if (got < 0) {
> @@ -1594,20 +1610,42 @@ static errcode_t copy_file(int fd, ext2_ino_t newfile)
>  			goto fail;
>  		}
>  		ptr = buf;
> +
> +		/* Sparse copy */
> +		if (make_holes) {
> +			if (!(zeromem = (char *) calloc(got, 1))) {

Maybe ext2fs_get_memzero()?  And I suspect you can allocate a bufsize-sized
zeromem outside the while loop.  Chances are pretty good that if make_holes,
then buf_size won't be greater than 4096 anyway.

--D

> +				fprintf(stderr, "copy_file: can't allocate buffer\n");
> +				return;
> +			}
> +			/* Check whether all is zero */
> +			cmp = memcmp(ptr, zeromem, got);
> +			/* Free it as early as possible */
> +			free(zeromem);
> +			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);
>  			if (retval)
>  				goto fail;
> -
>  			got -= written;
>  			ptr += written;
>  		}
>  	}
> +	free(buf);
>  	retval = ext2fs_file_close(e2_file);
>  	return retval;
>  
>  fail:
> +	free(buf);
>  	(void) ext2fs_file_close(e2_file);
>  	return retval;
>  }
> @@ -1620,6 +1658,8 @@ 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))
> @@ -1684,7 +1724,15 @@ 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);
>  	}
> -- 
> 1.8.1.2
> 
> --
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Robert Yang - July 29, 2013, 7:11 a.m.
On 07/27/2013 12:02 AM, Darrick J. Wong wrote:
> On Fri, Jul 26, 2013 at 06:30:57PM +0800, Robert Yang wrote:
>> 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.
>>
>> Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
>> Acked-by: Darren Hart <dvhart@linux.intel.com>
>> ---
>>   debugfs/debugfs.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++-----
>>   1 file changed, 53 insertions(+), 5 deletions(-)
>>
>> diff --git a/debugfs/debugfs.c b/debugfs/debugfs.c
>> index b77d0b5..0379f38 100644
>> --- a/debugfs/debugfs.c
>> +++ b/debugfs/debugfs.c
>> @@ -37,6 +37,16 @@ extern char *optarg;
>>   #include "../version.h"
>>   #include "jfs_user.h"
>>
>> +/* 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;
>> @@ -1571,22 +1581,28 @@ 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		*zeromem;
>> +	int		cmp;
>>
>>   	retval = ext2fs_file_open(current_fs, newfile,
>>   				  EXT2_FILE_WRITE, &e2_file);
>>   	if (retval)
>>   		return retval;
>>
>> +	if (!(buf = (char *) malloc(bufsize))){
>> +		fprintf(stderr, "copy_file: can't allocate buffer\n");
>> +		return;
>> +	}
>>   	while (1) {
>> -		got = read(fd, buf, sizeof(buf));
>> +		got = read(fd, buf, bufsize);
>>   		if (got == 0)
>>   			break;
>>   		if (got < 0) {
>> @@ -1594,20 +1610,42 @@ static errcode_t copy_file(int fd, ext2_ino_t newfile)
>>   			goto fail;
>>   		}
>>   		ptr = buf;
>> +
>> +		/* Sparse copy */
>> +		if (make_holes) {
>> +			if (!(zeromem = (char *) calloc(got, 1))) {
>
> Maybe ext2fs_get_memzero()?  And I suspect you can allocate a bufsize-sized
> zeromem outside the while loop.  Chances are pretty good that if make_holes,
> then buf_size won't be greater than 4096 anyway.

Thanks, sounds great, my testing shows that it is faster for copying the
large sparse file after move the ext2fs_get_memzero() out of the while loop,
and didn't have any obvious impaction for non-sparse file, I will update it
and send a V3.

// Robert

>
> --D
>
>> +				fprintf(stderr, "copy_file: can't allocate buffer\n");
>> +				return;
>> +			}
>> +			/* Check whether all is zero */
>> +			cmp = memcmp(ptr, zeromem, got);
>> +			/* Free it as early as possible */
>> +			free(zeromem);
>> +			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);
>>   			if (retval)
>>   				goto fail;
>> -
>>   			got -= written;
>>   			ptr += written;
>>   		}
>>   	}
>> +	free(buf);
>>   	retval = ext2fs_file_close(e2_file);
>>   	return retval;
>>
>>   fail:
>> +	free(buf);
>>   	(void) ext2fs_file_close(e2_file);
>>   	return retval;
>>   }
>> @@ -1620,6 +1658,8 @@ 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))
>> @@ -1684,7 +1724,15 @@ 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);
>>   	}
>> --
>> 1.8.1.2
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
>
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Patch

diff --git a/debugfs/debugfs.c b/debugfs/debugfs.c
index b77d0b5..0379f38 100644
--- a/debugfs/debugfs.c
+++ b/debugfs/debugfs.c
@@ -37,6 +37,16 @@  extern char *optarg;
 #include "../version.h"
 #include "jfs_user.h"
 
+/* 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;
@@ -1571,22 +1581,28 @@  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		*zeromem;
+	int		cmp;
 
 	retval = ext2fs_file_open(current_fs, newfile,
 				  EXT2_FILE_WRITE, &e2_file);
 	if (retval)
 		return retval;
 
+	if (!(buf = (char *) malloc(bufsize))){
+		fprintf(stderr, "copy_file: can't allocate buffer\n");
+		return;
+	}
 	while (1) {
-		got = read(fd, buf, sizeof(buf));
+		got = read(fd, buf, bufsize);
 		if (got == 0)
 			break;
 		if (got < 0) {
@@ -1594,20 +1610,42 @@  static errcode_t copy_file(int fd, ext2_ino_t newfile)
 			goto fail;
 		}
 		ptr = buf;
+
+		/* Sparse copy */
+		if (make_holes) {
+			if (!(zeromem = (char *) calloc(got, 1))) {
+				fprintf(stderr, "copy_file: can't allocate buffer\n");
+				return;
+			}
+			/* Check whether all is zero */
+			cmp = memcmp(ptr, zeromem, got);
+			/* Free it as early as possible */
+			free(zeromem);
+			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);
 			if (retval)
 				goto fail;
-
 			got -= written;
 			ptr += written;
 		}
 	}
+	free(buf);
 	retval = ext2fs_file_close(e2_file);
 	return retval;
 
 fail:
+	free(buf);
 	(void) ext2fs_file_close(e2_file);
 	return retval;
 }
@@ -1620,6 +1658,8 @@  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))
@@ -1684,7 +1724,15 @@  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);
 	}