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e2fsprogs
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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.

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Acked-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
debian-1.42.9
Robert Yang 2013-10-13 22:08:40 -04:00 committed by Theodore Ts'o
parent 355ffb2ff5
commit c756ec4217
1 changed files with 58 additions and 4 deletions
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62
debugfs/debugfs.c
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@ -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);
}