]> git.ipfire.org Git - thirdparty/e2fsprogs.git/commitdiff
copy-in: for files, only iterate file blocks that are mapped
authorDarrick J. Wong <darrick.wong@oracle.com>
Tue, 5 May 2015 14:46:48 +0000 (10:46 -0400)
committerTheodore Ts'o <tytso@mit.edu>
Tue, 5 May 2015 14:46:48 +0000 (10:46 -0400)
Rewrite the file copy-in algorithm to detect smaller holes in the
files we're copying in.  Use SEEK_DATA/SEEK_HOLE/FIEMAP when available
to skip known empty parts.  This fixes the particular bug where zeroed
blocks on a system with 64k pages are needlessly copied into a
4k-block filesystem.  It also saves time by skipping parts we know to
be zeroed.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
misc/create_inode.c

index 3bc05157a538061f8cc015bef31b33a86dd9be38..8ab546eb585e72c41039ea8fd6dc6754c7af919b 100644 (file)
@@ -9,12 +9,22 @@
  * %End-Header%
  */
 
+#define _FILE_OFFSET_BITS       64
+#define _LARGEFILE64_SOURCE     1
+#define _GNU_SOURCE            1
+
+#include "config.h"
 #include <time.h>
+#include <sys/types.h>
 #include <unistd.h>
 #include <limits.h> /* for PATH_MAX */
 #ifdef HAVE_ATTR_XATTR_H
 #include <attr/xattr.h>
 #endif
+#include <sys/ioctl.h>
+#include <ext2fs/ext2fs.h>
+#include <ext2fs/ext2_types.h>
+#include <ext2fs/fiemap.h>
 
 #include "create_inode.h"
 #include "nls-enable.h"
 #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
+#define COPY_FILE_BUFLEN       65536
 
 static int ext2_file_type(unsigned int mode)
 {
@@ -139,10 +142,9 @@ static errcode_t set_inode_xattr(ext2_filsys fs, ext2_ino_t ino, const char *fil
 {
 #ifdef HAVE_LLISTXATTR
        errcode_t                       retval, close_retval;
-       struct ext2_inode               inode;
        struct ext2_xattr_handle        *handle;
        ssize_t                         size, value_size;
-       char                            *list;
+       char                            *list = NULL;
        int                             i;
 
        size = llistxattr(filename, NULL, 0);
@@ -382,82 +384,202 @@ try_again:
        return retval;
 }
 
-static errcode_t copy_file(ext2_filsys fs, int fd, ext2_ino_t newfile,
-                          int bufsize, int make_holes)
+#if !defined HAVE_PREAD64 && !defined HAVE_PREAD
+static ssize_t my_pread(int fd, const void *buf, size_t count, off_t offset)
 {
-       ext2_file_t     e2_file;
-       errcode_t       retval, close_ret;
-       int             got;
-       unsigned int    written;
-       char            *buf;
-       char            *ptr;
-       char            *zero_buf;
-       int             cmp;
-
-       retval = ext2fs_file_open(fs, newfile,
-                                 EXT2_FILE_WRITE, &e2_file);
-       if (retval)
-               return retval;
-
-       retval = ext2fs_get_mem(bufsize, &buf);
-       if (retval) {
-               com_err("copy_file", retval, "can't allocate buffer\n");
-               goto out_close;
-       }
+       if (lseek(fd, offset, SEEK_SET) < 0)
+               return 0;
 
-       /* 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 zero buffer\n");
-               goto out_free_buf;
-       }
+       return read(fd, buf, count);
+}
+#endif /* !defined HAVE_PREAD64 && !defined HAVE_PREAD */
 
-       while (1) {
-               got = read(fd, buf, bufsize);
-               if (got == 0)
-                       break;
+static errcode_t copy_file_range(ext2_filsys fs, int fd, ext2_file_t e2_file,
+                                off_t start, off_t end, char *buf,
+                                char *zerobuf)
+{
+       off_t off, bpos;
+       ssize_t got, blen;
+       unsigned int written;
+       char *ptr;
+       errcode_t err = 0;
+
+       for (off = start; off < end; off += COPY_FILE_BUFLEN) {
+#ifdef HAVE_PREAD64
+               got = pread64(fd, buf, COPY_FILE_BUFLEN, off);
+#elif HAVE_PREAD
+               got = pread(fd, buf, COPY_FILE_BUFLEN, off);
+#else
+               got = my_pread(fd, buf, COPY_FILE_BUFLEN, off);
+#endif
                if (got < 0) {
-                       retval = errno;
+                       err = errno;
                        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)
+               for (bpos = 0, ptr = buf; bpos < got; bpos += fs->blocksize) {
+                       blen = fs->blocksize;
+                       if (blen > got - bpos)
+                               blen = got - bpos;
+                       if (memcmp(ptr, zerobuf, blen) == 0) {
+                               ptr += blen;
+                               continue;
+                       }
+                       err = ext2fs_file_lseek(e2_file, off + bpos,
+                                               EXT2_SEEK_SET, NULL);
+                       if (err)
+                               goto fail;
+                       while (blen > 0) {
+                               err = ext2fs_file_write(e2_file, ptr, blen,
+                                                       &written);
+                               if (err)
+                                       goto fail;
+                               if (written == 0) {
+                                       err = EIO;
                                        goto fail;
-                               got = 0;
+                               }
+                               blen -= written;
+                               ptr += written;
                        }
                }
+       }
+fail:
+       return err;
+}
 
-               /* Normal copy */
-               while (got > 0) {
-                       retval = ext2fs_file_write(e2_file, ptr,
-                                                  got, &written);
-                       if (retval)
-                               goto fail;
-
-                       got -= written;
-                       ptr += written;
+static errcode_t try_lseek_copy(ext2_filsys fs, int fd, struct stat *statbuf,
+                               ext2_file_t e2_file, char *buf, char *zerobuf)
+{
+#if defined(SEEK_DATA) && defined(SEEK_HOLE)
+       off_t data = 0, hole;
+       off_t data_blk, hole_blk;
+       errcode_t err;
+
+       /* Try to use SEEK_DATA and SEEK_HOLE */
+       while (data < statbuf->st_size) {
+               data = lseek(fd, data, SEEK_DATA);
+               if (data < 0) {
+                       if (errno == ENXIO)
+                               break;
+                       return EXT2_ET_UNIMPLEMENTED;
                }
+               hole = lseek(fd, data, SEEK_HOLE);
+               if (hole < 0)
+                       return EXT2_ET_UNIMPLEMENTED;
+
+               data_blk = data & ~(fs->blocksize - 1);
+               hole_blk = (hole + (fs->blocksize - 1)) & ~(fs->blocksize - 1);
+               err = copy_file_range(fs, fd, e2_file, data_blk, hole_blk, buf,
+                                     zerobuf);
+               if (err)
+                       return err;
+
+               data = hole;
        }
 
-fail:
-       ext2fs_free_mem(&zero_buf);
-out_free_buf:
+       return err;
+#else
+       return EXT2_ET_UNIMPLEMENTED;
+#endif /* SEEK_DATA and SEEK_HOLE */
+}
+
+static errcode_t try_fiemap_copy(ext2_filsys fs, int fd, ext2_file_t e2_file,
+                                char *buf, char *zerobuf)
+{
+#if defined(FS_IOC_FIEMAP)
+#define EXTENT_MAX_COUNT 512
+       struct fiemap *fiemap_buf;
+       struct fiemap_extent *ext_buf, *ext;
+       int ext_buf_size, fie_buf_size;
+       off_t pos = 0;
+       unsigned int i;
+       errcode_t err;
+
+       ext_buf_size = EXTENT_MAX_COUNT * sizeof(struct fiemap_extent);
+       fie_buf_size = sizeof(struct fiemap) + ext_buf_size;
+
+       err = ext2fs_get_memzero(fie_buf_size, &fiemap_buf);
+       if (err)
+               return err;
+
+       ext_buf = fiemap_buf->fm_extents;
+       memset(fiemap_buf, 0, fie_buf_size);
+       fiemap_buf->fm_length = FIEMAP_MAX_OFFSET;
+       fiemap_buf->fm_flags |= FIEMAP_FLAG_SYNC;
+       fiemap_buf->fm_extent_count = EXTENT_MAX_COUNT;
+
+       do {
+               fiemap_buf->fm_start = pos;
+               memset(ext_buf, 0, ext_buf_size);
+               err = ioctl(fd, FS_IOC_FIEMAP, fiemap_buf);
+               if (err < 0 && (errno == EOPNOTSUPP || errno == ENOTTY)) {
+                       err = EXT2_ET_UNIMPLEMENTED;
+                       goto out;
+               } else if (err < 0 || fiemap_buf->fm_mapped_extents == 0) {
+                       err = errno;
+                       goto out;
+               }
+               for (i = 0, ext = ext_buf; i < fiemap_buf->fm_mapped_extents;
+                    i++, ext++) {
+                       err = copy_file_range(fs, fd, e2_file, ext->fe_logical,
+                                             ext->fe_logical + ext->fe_length,
+                                             buf, zerobuf);
+                       if (err)
+                               goto out;
+               }
+
+               ext--;
+               /* Record file's logical offset this time */
+               pos = ext->fe_logical + ext->fe_length;
+               /*
+                * If fm_extents array has been filled and
+                * there are extents left, continue to cycle.
+                */
+       } while (fiemap_buf->fm_mapped_extents == EXTENT_MAX_COUNT &&
+                !(ext->fe_flags & FIEMAP_EXTENT_LAST));
+out:
+       ext2fs_free_mem(&fiemap_buf);
+       return err;
+#else
+       return EXT2_ET_UNIMPLEMENTED;
+#endif /* FS_IOC_FIEMAP */
+}
+
+static errcode_t copy_file(ext2_filsys fs, int fd, struct stat *statbuf,
+                          ext2_ino_t ino)
+{
+       ext2_file_t e2_file;
+       char *buf = NULL, *zerobuf = NULL;
+       errcode_t err, close_err;
+
+       err = ext2fs_file_open(fs, ino, EXT2_FILE_WRITE, &e2_file);
+       if (err)
+               return err;
+
+       err = ext2fs_get_mem(COPY_FILE_BUFLEN, &buf);
+       if (err)
+               goto out;
+
+       err = ext2fs_get_memzero(fs->blocksize, &zerobuf);
+       if (err)
+               goto out;
+
+       err = try_lseek_copy(fs, fd, statbuf, e2_file, buf, zerobuf);
+       if (err != EXT2_ET_UNIMPLEMENTED)
+               goto out;
+
+       err = try_fiemap_copy(fs, fd, e2_file, buf, zerobuf);
+       if (err != EXT2_ET_UNIMPLEMENTED)
+               goto out;
+
+       err = copy_file_range(fs, fd, e2_file, 0, statbuf->st_size, buf,
+                             zerobuf);
+out:
+       ext2fs_free_mem(&zerobuf);
        ext2fs_free_mem(&buf);
-out_close:
-       close_ret = ext2fs_file_close(e2_file);
-       if (retval == 0)
-               retval = close_ret;
-       return retval;
+       close_err = ext2fs_file_close(e2_file);
+       if (err == 0)
+               err = close_err;
+       return err;
 }
 
 static int is_hardlink(struct hdlinks_s *hdlinks, dev_t dev, ino_t ino)
@@ -481,8 +603,6 @@ errcode_t do_write_internal(ext2_filsys fs, ext2_ino_t cwd, const char *src,
        ext2_ino_t      newfile;
        errcode_t       retval;
        struct ext2_inode inode;
-       int             bufsize = IO_BUFSIZE;
-       int             make_holes = 0;
 
        fd = ext2fs_open_file(src, O_RDONLY, 0);
        if (fd < 0) {
@@ -570,17 +690,9 @@ errcode_t do_write_internal(ext2_filsys fs, ext2_ino_t cwd, const char *src,
                }
        }
        if (LINUX_S_ISREG(inode.i_mode)) {
-               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(fs, fd, newfile, bufsize, make_holes);
+               retval = copy_file(fs, fd, &statbuf, newfile);
                if (retval)
-                       com_err("copy_file", retval, 0);
+                       com_err("copy_file", retval, _("while copying %s"), src);
        }
        close(fd);