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List: coreutils-bug
Subject: bug#6131: [PATCH]: fiemap support for efficient sparse file copy
From: "jeff.liu" <jeff.liu () oracle ! com>
Date: 2010-07-20 15:24:21
Message-ID: 4C45BFA5.5000809 () oracle ! com
[Download RAW message or body]
Hello All,
Below is my patches to isolate the extents scan and fetch functions in a new module to improve its
extendibility.
It introduce a new file 'src/extent-scan.c' to place those functions, and then call those functions
from extents_copy() at copy_reg() to process the regular file copy.
In addition to this, another major change is to copy all data if '--sparse=never' option is
specified. It write all data to destination file but using extents_copy() if available for
efficient read source file, and it try to figure out the holes between the previous and current
extents, and call fill_with_holes_ok() to write zeros as holes to the destination file if it is.
Call file_with_holes_ok() to write zeros up to the source file size if hit the last extent of the
source file and there is a hole behind it.
I have not implement the solaris lseek(2) at the moment for lack of solaris environment, it need to
delay a period of time.
According to my tryout, it works for those 4 filesystems in common use, you all know.
As usual, any comments are welcome!
From 70773fdf1d85ba070e054b0467a7a0e1e2b00ea8 Mon Sep 17 00:00:00 2001
From: Jie Liu <jeff.liu@oracle.com>
Date: Tue, 20 Jul 2010 20:35:25 +0800
Subject: [PATCH 1/3] cp: delete fiemap_copy() related stuff from copy.c
* delete fiemap_copy(), now it is implemented as a module.
Signed-off-by: Jie Liu <jeff.liu@oracle.com>
---
src/copy.c | 171 ------------------------------------------------------------
1 files changed, 0 insertions(+), 171 deletions(-)
diff --git a/src/copy.c b/src/copy.c
index f48c74d..171499c 100644
--- a/src/copy.c
+++ b/src/copy.c
@@ -63,10 +63,6 @@
#include <sys/ioctl.h>
-#ifndef HAVE_FIEMAP
-# include "fiemap.h"
-#endif
-
#ifndef HAVE_FCHOWN
# define HAVE_FCHOWN false
# define fchown(fd, uid, gid) (-1)
@@ -153,153 +149,6 @@ clone_file (int dest_fd, int src_fd)
#endif
}
-#ifdef __linux__
-# ifndef FS_IOC_FIEMAP
-# define FS_IOC_FIEMAP _IOWR ('f', 11, struct fiemap)
-# endif
-/* Perform a FIEMAP copy, if possible.
- Call ioctl(2) with FS_IOC_FIEMAP (available in linux 2.6.27) to
- obtain a map of file extents excluding holes. This avoids the
- overhead of detecting holes in a hole-introducing/preserving copy,
- and thus makes copying sparse files much more efficient. Upon a
- successful copy, return true. If the initial ioctl fails, set
- *NORMAL_COPY_REQUIRED to true and return false. Upon any other
- failure, set *NORMAL_COPY_REQUIRED to false and return false. */
-static bool
-fiemap_copy (int src_fd, int dest_fd, size_t buf_size,
- off_t src_total_size, char const *src_name,
- char const *dst_name, bool *normal_copy_required)
-{
- bool last = false;
- union { struct fiemap f; char c[4096]; } fiemap_buf;
- struct fiemap *fiemap = &fiemap_buf.f;
- struct fiemap_extent *fm_ext = &fiemap->fm_extents[0];
- enum { count = (sizeof fiemap_buf - sizeof *fiemap) / sizeof *fm_ext };
- verify (count != 0);
-
- off_t last_ext_logical = 0;
- uint64_t last_ext_len = 0;
- uint64_t last_read_size = 0;
- unsigned int i = 0;
- *normal_copy_required = false;
-
- /* This is required at least to initialize fiemap->fm_start,
- but also serves (in mid 2010) to appease valgrind, which
- appears not to know the semantics of the FIEMAP ioctl. */
- memset (&fiemap_buf, 0, sizeof fiemap_buf);
-
- do
- {
- fiemap->fm_length = FIEMAP_MAX_OFFSET;
- fiemap->fm_flags = FIEMAP_FLAG_SYNC;
- fiemap->fm_extent_count = count;
-
- /* When ioctl(2) fails, fall back to the normal copy only if it
- is the first time we met. */
- if (ioctl (src_fd, FS_IOC_FIEMAP, fiemap) < 0)
- {
- /* If the first ioctl fails, tell the caller that it is
- ok to proceed with a normal copy. */
- if (i == 0)
- *normal_copy_required = true;
- else
- {
- /* If the second or subsequent ioctl fails, diagnose it,
- since it ends up causing the entire copy/cp to fail. */
- error (0, errno, _("%s: FIEMAP ioctl failed"), quote (src_name));
- }
- return false;
- }
-
- /* If 0 extents are returned, then more ioctls are not needed. */
- if (fiemap->fm_mapped_extents == 0)
- break;
-
- for (i = 0; i < fiemap->fm_mapped_extents; i++)
- {
- assert (fm_ext[i].fe_logical <= OFF_T_MAX);
-
- off_t ext_logical = fm_ext[i].fe_logical;
- uint64_t ext_len = fm_ext[i].fe_length;
-
- if (lseek (src_fd, ext_logical, SEEK_SET) < 0)
- {
- error (0, errno, _("cannot lseek %s"), quote (src_name));
- return false;
- }
-
- if (lseek (dest_fd, ext_logical, SEEK_SET) < 0)
- {
- error (0, errno, _("cannot lseek %s"), quote (dst_name));
- return false;
- }
-
- if (fm_ext[i].fe_flags & FIEMAP_EXTENT_LAST)
- {
- last_ext_logical = ext_logical;
- last_ext_len = ext_len;
- last = true;
- }
-
- while (ext_len)
- {
- char buf[buf_size];
-
- /* Avoid reading into the holes if the left extent
- length is shorter than the buffer size. */
- if (ext_len < buf_size)
- buf_size = ext_len;
-
- ssize_t n_read = read (src_fd, buf, buf_size);
- if (n_read < 0)
- {
-#ifdef EINTR
- if (errno == EINTR)
- continue;
-#endif
- error (0, errno, _("reading %s"), quote (src_name));
- return false;
- }
-
- if (n_read == 0)
- {
- /* Figure out how many bytes read from the last extent. */
- last_read_size = last_ext_len - ext_len;
- break;
- }
-
- if (full_write (dest_fd, buf, n_read) != n_read)
- {
- error (0, errno, _("writing %s"), quote (dst_name));
- return false;
- }
-
- ext_len -= n_read;
- }
- }
-
- fiemap->fm_start = fm_ext[i - 1].fe_logical + fm_ext[i - 1].fe_length;
-
- } while (! last);
-
- /* If a file ends up with holes, the sum of the last extent logical offset
- and the read-returned size will be shorter than the actual size of the
- file. Use ftruncate to extend the length of the destination file. */
- if (last_ext_logical + last_read_size < src_total_size)
- {
- if (ftruncate (dest_fd, src_total_size) < 0)
- {
- error (0, errno, _("failed to extend %s"), quote (dst_name));
- return false;
- }
- }
-
- return true;
-}
-#else
-static bool fiemap_copy (ignored) { errno == ENOTSUP; return false; }
-#endif
-
/* FIXME: describe */
/* FIXME: rewrite this to use a hash table so we avoid the quadratic
performance hit that's probably noticeable only on trees deeper
@@ -830,25 +679,6 @@ copy_reg (char const *src_name, char const *dst_name,
#endif
}
- if (make_holes)
- {
- bool require_normal_copy;
- /* Perform efficient FIEMAP copy for sparse files, fall back to the
- standard copy only if the ioctl(2) fails. */
- if (fiemap_copy (source_desc, dest_desc, buf_size,
- src_open_sb.st_size, src_name,
- dst_name, &require_normal_copy))
- goto preserve_metadata;
- else
- {
- if (! require_normal_copy)
- {
- return_val = false;
- goto close_src_and_dst_desc;
- }
- }
- }
-
/* If not making a sparse file, try to use a more-efficient
buffer size. */
if (! make_holes)
@@ -977,7 +807,6 @@ copy_reg (char const *src_name, char const *dst_name,
}
}
-preserve_metadata:
if (x->preserve_timestamps)
{
struct timespec timespec[2];
--
1.5.4.3
From f083f1a52ec5baba90aa228c1053f4a32127b3b2 Mon Sep 17 00:00:00 2001
From: Jie Liu <jeff.liu@oracle.com>
Date: Tue, 20 Jul 2010 23:10:29 +0800
Subject: [PATCH 2/3] cp: add a new module for scanning extents
* src/extent-scan.c: Source code for scanning extents.
Call init_extent_scan() to return an extents map.
Call get_next_extent() to get the next extent for each iteration.
Call close_extent_scan() to tear down the scan, it now do nothing.
* src/extent-scan.h: Header file of extent-scan.c.
* src/Makefile.am: Reference it.
Signed-off-by: Jie Liu <jeff.liu@oracle.com>
---
src/Makefile.am | 3 +-
src/extent-scan.c | 137 +++++++++++++++++++++++++++++++++++++++++++++++++++++
src/extent-scan.h | 25 ++++++++++
3 files changed, 164 insertions(+), 1 deletions(-)
create mode 100644 src/extent-scan.c
create mode 100644 src/extent-scan.h
diff --git a/src/Makefile.am b/src/Makefile.am
index 7d56312..fb8186c 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -145,6 +145,7 @@ noinst_HEADERS = \
copy.h \
cp-hash.h \
dircolors.h \
+ extent-scan.h \
fiemap.h \
fs.h \
group-list.h \
@@ -459,7 +460,7 @@ uninstall-local:
fi; \
fi
-copy_sources = copy.c cp-hash.c
+copy_sources = copy.c cp-hash.c extent-scan.c
# Use `ginstall' in the definition of PROGRAMS and in dependencies to avoid
# confusion with the `install' target. The install rule transforms `ginstall'
diff --git a/src/extent-scan.c b/src/extent-scan.c
new file mode 100644
index 0000000..c4085e0
--- /dev/null
+++ b/src/extent-scan.c
@@ -0,0 +1,137 @@
+/* extent-scan.c -- core functions for scanning extents
+ Copyright (C) 2010 Free Software Foundation, Inc.
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+ Written by Jie Liu (jeff.liu@oracle.com). */
+
+#include <config.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/ioctl.h>
+
+#include "system.h"
+#include "extent-scan.h"
+#include "error.h"
+#include "quote.h"
+
+#ifndef HAVE_FIEMAP
+# include "fiemap.h"
+#endif
+
+/* The number of extents currently scan returned. */
+static size_t current_scanned_extents_count = 0;
+
+#ifdef __linux__
+# ifndef FS_IOC_FIEMAP
+# define FS_IOC_FIEMAP _IOWR ('f', 11, struct fiemap)
+# endif
+/* Call ioctl(2) with FS_IOC_FIEMAP (available in linux 2.6.27) to
+ obtain a map of file extents excluding holes. */
+extern void *
+init_extent_scan (int src_fd, const char *src_name,
+ bool *normal_copy_required,
+ bool *hit_last_extent)
+{
+ union { struct fiemap f; char c[4096]; } fiemap_buf;
+ struct fiemap *fiemap = &fiemap_buf.f;
+ struct fiemap_extent *fm_extents = &fiemap->fm_extents[0];
+ enum { count = (sizeof fiemap_buf - sizeof *fiemap) / sizeof *fm_extents };
+ verify (count != 0);
+ static uint64_t next_map_start = 0;
+
+ /* This is required at least to initialize fiemap->fm_start,
+ * but also serves (in mid 2010) to appease valgrind, which
+ * appears not to know the semantics of the FIEMAP ioctl. */
+ memset (&fiemap_buf, 0, sizeof fiemap_buf);
+
+ fiemap->fm_start = next_map_start;
+ fiemap->fm_flags = FIEMAP_FLAG_SYNC;
+ fiemap->fm_extent_count = count;
+ fiemap->fm_length = FIEMAP_MAX_OFFSET - next_map_start;
+
+ /* When ioctl(2) fails, fall back to the normal copy only if it
+ is the first time we met. */
+ if (ioctl (src_fd, FS_IOC_FIEMAP, fiemap) < 0)
+ {
+ error (0, errno, _("%s: FIEMAP ioctl failed"), quote (src_name));
+
+ if (next_map_start == 0)
+ *normal_copy_required = true;
+
+ return NULL;
+ }
+
+ /* If 0 extents are returned, then more init_extent_scan() are not needed. */
+ if (fiemap->fm_mapped_extents == 0)
+ {
+ *hit_last_extent = true;
+ return NULL;
+ }
+
+ current_scanned_extents_count = fiemap->fm_mapped_extents;
+ unsigned int last_extent_index = current_scanned_extents_count - 1;
+
+ if (fm_extents[last_extent_index].fe_flags & FIEMAP_EXTENT_LAST)
+ {
+ *hit_last_extent = true;
+ return fm_extents;
+ }
+
+ next_map_start = fm_extents[last_extent_index].fe_logical +
+ fm_extents[last_extent_index].fe_length;
+
+ return fm_extents;
+}
+
+/* Return an extent's logical offset and length for each iteration. */
+extern bool
+get_next_extent (void *scanned_extents, off_t *extent_logical,
+ uint64_t *extent_length)
+{
+ static size_t i = 0;
+ struct fiemap_extent *fm_extents = (struct fiemap_extent *) scanned_extents;
+
+ if (i < current_scanned_extents_count)
+ {
+ *extent_logical = fm_extents[i].fe_logical;
+ *extent_length = fm_extents[i].fe_length;
+ i++;
+ return true;
+ }
+
+ return false;
+}
+
+extern void
+close_extent_scan (void)
+{
+ return ;
+}
+#else
+extent void *
+init_extent_scan (int src_fd, const char *src_name,
+ bool *hit_last_extent, bool *normal_copy_required)
+{
+ *normal_copy_required = true;
+ errno = ENOTSUP;
+ (void) src_fd;
+ (void) src_name;
+ (void) hit_last_extent;
+ (void) normal_copy_required;
+ return false;
+}
+extern bool get_next_extent (ignored) { errno = ENOTSUP; return false; }
+extern void close_extent_scan (ignored) { error = ENOTSUP; return ; }
+#endif
diff --git a/src/extent-scan.h b/src/extent-scan.h
new file mode 100644
index 0000000..e7e373f
--- /dev/null
+++ b/src/extent-scan.h
@@ -0,0 +1,25 @@
+/* core functions for efficient reading sparse files
+ Copyright (C) 2010 Free Software Foundation, Inc.
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+#ifndef SPARSE_CORE_H
+# define SPARSE_CORE_H
+
+void *init_extent_scan (int src_fd, const char *src_name,
+ bool *normal_copy_required,
+ bool *hit_last_extent);
+bool get_next_extent (void *scanned_extents, off_t *extent_logical, uint64_t *extent_length);
+void close_extent_scan (void);
+#endif /* SPARSE_CORE_H */
--
1.5.4.3
From f23169c2c1721b8888dccb77000f79ddf9804df0 Mon Sep 17 00:00:00 2001
From: Jie Liu <jeff.liu@oracle.com>
Date: Tue, 20 Jul 2010 23:11:08 +0800
Subject: [PATCH 3/3] cp: add extents_copy() for efficient sparse file copy
* src/copy.c (copy_reg): Now, `cp' attempt to make use of the new extent scan
module for efficient sparse file copy through extents_copy(), fall back to a
normal copy if the underlaying file system does not support it.
We honor --sparse=never by writing all data but use extents scan if available
to read source file for the efficiently read.
* src/copy.c: Add fill_with_holes_ok() for write zeros as holes to destination file.
* po/POTFILES.in: add extent-scan.c to it.
Signed-off-by: Jie Liu <jeff.liu@oracle.com>
---
po/POTFILES.in | 1 +
src/copy.c | 190 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 191 insertions(+), 0 deletions(-)
diff --git a/po/POTFILES.in b/po/POTFILES.in
index c862877..2ac1993 100644
--- a/po/POTFILES.in
+++ b/po/POTFILES.in
@@ -60,6 +60,7 @@ src/echo.c
src/env.c
src/expand.c
src/expr.c
+src/extent-scan.c
src/factor.c
src/false.c
src/fmt.c
diff --git a/src/copy.c b/src/copy.c
index 171499c..6d89bbe 100644
--- a/src/copy.c
+++ b/src/copy.c
@@ -36,6 +36,7 @@
#include "copy.h"
#include "cp-hash.h"
#include "error.h"
+#include "extent-scan.h"
#include "fcntl--.h"
#include "file-set.h"
#include "filemode.h"
@@ -149,6 +150,176 @@ clone_file (int dest_fd, int src_fd)
#endif
}
+/* Write zeros as holes to the destination file. */
+static bool
+fill_with_holes_ok (int dest_fd, const char *dst_name,
+ char *buf, size_t buf_size,
+ uint64_t holes_len)
+{
+ while (buf_size < holes_len)
+ {
+ if (full_write (dest_fd, buf, buf_size) != buf_size)
+ {
+ error (0, errno, _("writing %s"), quote (dst_name));
+ return false;
+ }
+ holes_len -= buf_size;
+ }
+
+ if (0 < holes_len)
+ {
+ if (full_write (dest_fd, buf, holes_len) != holes_len)
+ {
+ error (0, errno, _("writing %s"), quote (dst_name));
+ return false;
+ }
+ }
+
+ return true;
+}
+
+/* Perform an efficient extents copy, if possible. This avoids
+ the overhead of detecting holes in hole-introducing/preserving
+ copy, and thus make copying sparse files much more efficient.
+ Upon a successful copy, return true. If the first initial extent
+ scan fails, set *NORMAL_COPY_REQUIRED to true and return false.
+ Upon any other failure, set *NORMAL_COPY_REQUIRED to false and
+ return false. */
+static bool
+extents_copy (int source_desc, int dest_desc,
+ char *buf, size_t buf_size,
+ const char *src_name, const char *dst_name,
+ bool make_holes, size_t src_total_size,
+ bool *require_normal_copy)
+{
+ bool init_extent_scan_failed = false;
+ bool hit_last_extent = false;
+ void *scanned_extents;
+ off_t last_ext_logical = 0;
+ off_t ext_logical = 0;
+ uint64_t last_ext_len = 0;
+ uint64_t ext_len = 0;
+ uint64_t holes_len = 0;
+ uint64_t last_read_size = 0;
+
+ if (! make_holes)
+ memset (buf, 0, buf_size);
+
+ do
+ {
+ scanned_extents = init_extent_scan (source_desc, src_name,
+ &init_extent_scan_failed,
+ &hit_last_extent);
+ if (init_extent_scan_failed)
+ {
+ *require_normal_copy = true;
+ return false;
+ }
+
+ while (get_next_extent (scanned_extents, &ext_logical, &ext_len))
+ {
+ assert (ext_logical <= OFF_T_MAX);
+
+ if (lseek (source_desc, ext_logical, SEEK_SET) < 0)
+ {
+ error (0, errno, _("cannot lseek %s"), quote (src_name));
+ return false;
+ }
+
+ if (make_holes)
+ {
+ if (lseek (dest_desc, ext_logical, SEEK_SET) < 0)
+ {
+ error (0, errno, _("cannot lseek %s"), quote (dst_name));
+ return false;
+ }
+ }
+ else
+ {
+ /* If not making a sparse file, write zeros to the destination
+ file if there is a hole between the last and current extent. */
+ if (last_ext_logical + last_ext_len < ext_logical)
+ {
+ holes_len = ext_logical - last_ext_logical - last_ext_len;
+ if (! fill_with_holes_ok (dest_desc, dst_name, buf, buf_size, holes_len))
+ return false;
+ }
+ }
+
+ last_ext_logical = ext_logical;
+ last_ext_len = ext_len;
+
+ last_read_size = 0;
+ while (ext_len)
+ {
+ /* Avoid reading into the holes if the left extent
+ length is shorter than the buffer size. */
+ if (ext_len < buf_size)
+ buf_size = ext_len;
+
+ ssize_t n_read = read (source_desc, buf, buf_size);
+ if (n_read < 0)
+ {
+#ifdef EINTR
+ if (errno == EINTR)
+ continue;
+#endif
+ error (0, errno, _("reading %s"), quote (src_name));
+ return false;
+ }
+
+ if (n_read == 0)
+ {
+ last_read_size = last_ext_len - ext_len;
+ break;
+ }
+
+ if (full_write (dest_desc, buf, n_read) != n_read)
+ {
+ error (0, errno, _("writing %s"), quote (dst_name));
+ return false;
+ }
+
+ ext_len -= n_read;
+ last_read_size += n_read;
+ }
+ }
+ } while (! hit_last_extent);
+
+ close_extent_scan ();
+
+ /* If a file ends up with holes, the sum of the last extent logical offset
+ and the read-returned size or the last extent length will be shorter than
+ the actual size of the file. Use ftruncate to extend the length of the
+ destination file if make_holes, or write zeros up to the actual size of the
+ file. */
+ if (make_holes)
+ {
+ if (last_ext_logical + last_read_size < src_total_size)
+ {
+ if (ftruncate (dest_desc, src_total_size) < 0)
+ {
+ error (0, errno, _("failed to extend %s"), quote (dst_name));
+ return false;
+ }
+ }
+ }
+ else
+ {
+ if (last_ext_logical + last_ext_len < src_total_size)
+ {
+ holes_len = src_total_size - last_ext_logical - last_ext_len;
+ if (0 < holes_len)
+ {
+ if (! fill_with_holes_ok (dest_desc, dst_name, buf, buf_size, holes_len))
+ return false;
+ }
+ }
+ }
+
+ return true;
+}
+
/* FIXME: describe */
/* FIXME: rewrite this to use a hash table so we avoid the quadratic
performance hit that's probably noticeable only on trees deeper
@@ -707,6 +878,24 @@ copy_reg (char const *src_name, char const *dst_name,
buf_alloc = xmalloc (buf_size + buf_alignment_slop);
buf = ptr_align (buf_alloc, buf_alignment);
+ bool require_normal_copy;
+ /* Perform efficient extents copy for sparse files, fall back to the
+ standard copy only if the first initial extent scan fails. If the
+ `--sparse=never' option was specified, we writing all data but use
+ extents copy if available to efficiently read. */
+ if (extents_copy (source_desc, dest_desc, buf, buf_size,
+ src_name, dst_name, make_holes,
+ src_open_sb.st_size, &require_normal_copy))
+ goto preserve_metadata;
+ else
+ {
+ if (! require_normal_copy)
+ {
+ return_val = false;
+ goto close_src_and_dst_desc;
+ }
+ }
+
while (true)
{
word *wp = NULL;
@@ -807,6 +996,7 @@ copy_reg (char const *src_name, char const *dst_name,
}
}
+preserve_metadata:
if (x->preserve_timestamps)
{
struct timespec timespec[2];
--
1.5.4.3
Thanks,
-Jeff
--
The knowledge you get, no matter how much it is, must be possessed yourself and nourished with your
own painstaking efforts and be your achievement through hard work.
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