On 10/15/2013 11:10 AM, Darrick J. Wong wrote:
On Mon, Aug 26, 2013 at 02:22:03PM +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@xxxxxxxxxxxxx> Acked-by: Darren Hart <dvhart@xxxxxxxxxxxxxxx> --- debugfs/debugfs.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 58 insertions(+), 4 deletions(-) diff --git a/debugfs/debugfs.c b/debugfs/debugfs.c index a6bc932..8c32eff 100644 --- 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; @@ -1575,22 +1585,37 @@ 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; + }Ugh. I probably could have whined about this not using ext2fs_get_mem, but more importantly clang whines about the undefined return value.
Thanks, Darrick:-) // Robert
I'll fix it and send out a patch with my next patchbomb. --D+ + /* 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) { @@ -1598,6 +1623,21 @@ 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); @@ -1608,10 +1648,14 @@ 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; } @@ -1624,6 +1668,8 @@ 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)) @@ -1699,7 +1745,15 @@ 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@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html-- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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