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GFile: Add Btrfs clone ioctl support

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The attached patch adds support for the btrfs "clone" ioctl which
makes Copy-on-Write reflinks, resulting in cheap O(1) copies when
source/destination are on the same filesystem. The ioctl itself is
quite straightforward, and GNU coreutils has had support since 7.5
(--reflink=auto --sparse=auto).

The ioctl only operates on regular files and symlinks, and always
follows symlinks; checks have been added accordingly.

This patch would be very useful for everyone who uses btrfs
filesystems (Meego folks for instance). On systems that don't have
btrfs, or if the the source is not on a btrfs filesystem, the ioctl
returns EINVAL, and the fallback code is triggered. Hence this will
cause no problems for non-btrfs users.

https://bugzilla.gnome.org/show_bug.cgi?id=626497
This commit is contained in:
Nirbheek Chauhan 2013-01-05 12:52:31 +05:30 committed by Colin Walters
parent f42347d82e
commit 5eba978497
2 changed files with 96 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
configure.ac
View File

@ -903,6 +903,7 @@ AC_CHECK_HEADERS([mntent.h sys/mnttab.h sys/vfstab.h sys/mntctl.h fstab.h])
AC_CHECK_HEADERS([sys/uio.h sys/mkdev.h])
AC_CHECK_HEADERS([linux/magic.h])
AC_CHECK_HEADERS([sys/prctl.h])
AC_CHECK_HEADERS([sys/ioctl.h])
AC_CHECK_HEADERS([sys/mount.h sys/sysctl.h], [], [],
[#if HAVE_SYS_PARAM_H

104
gio/gfile.c
View File

@ -23,17 +23,28 @@
*/
#include "config.h"
#if HAVE_SYS_IOCTL_H
#include <sys/ioctl.h>
#include <errno.h>
/* See linux.git/fs/btrfs/ioctl.h */
#define BTRFS_IOCTL_MAGIC 0x94
#define BTRFS_IOC_CLONE _IOW(BTRFS_IOCTL_MAGIC, 9, int)
#endif
#ifdef HAVE_SPLICE
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#endif
#include <string.h>
#include <sys/types.h>
#ifdef HAVE_PWD_H
#include <pwd.h>
#endif
#include "gfile.h"
#include "gvfs.h"
#include "gtask.h"
@ -2905,6 +2916,64 @@ splice_stream_with_progress (GInputStream *in,
}
#endif
#ifdef HAVE_SYS_IOCTL_H
static gboolean
btrfs_reflink_with_progress (GInputStream *in,
GOutputStream *out,
GFileInfo *info,
GCancellable *cancellable,
GFileProgressCallback progress_callback,
gpointer progress_callback_data,
GError **error)
{
goffset source_size;
int fd_in, fd_out;
int ret;
fd_in = g_file_descriptor_based_get_fd (G_FILE_DESCRIPTOR_BASED (in));
fd_out = g_file_descriptor_based_get_fd (G_FILE_DESCRIPTOR_BASED (out));
if (progress_callback)
source_size = g_file_info_get_size (info);
/* Btrfs clone ioctl properties:
* - Works at the inode level
* - Doesn't work with directories
* - Always follows symlinks (source and destination)
*
* By the time we get here, *in and *out are both regular files */
ret = ioctl (fd_out, BTRFS_IOC_CLONE, fd_in);
if (ret < 0)
{
if (errno == EXDEV)
g_set_error_literal (error, G_IO_ERROR,
G_IO_ERROR_NOT_SUPPORTED,
_("Copy (reflink/clone) between mounts is not supported"));
else if (errno == EINVAL)
g_set_error_literal (error, G_IO_ERROR,
G_IO_ERROR_NOT_SUPPORTED,
_("Copy (reflink/clone) is not supported or invalid"));
else
/* Most probably something odd happened; retry with fallback */
g_set_error_literal (error, G_IO_ERROR,
G_IO_ERROR_NOT_SUPPORTED,
_("Copy (reflink/clone) is not supported or didn't work"));
/* We retry with fallback for all error cases because Btrfs is currently
* unstable, and so we can't trust it to do clone properly.
* In addition, any hard errors here would cause the same failure in the
* fallback manual copy as well. */
return FALSE;
}
/* Make sure we send full copied size */
if (progress_callback)
progress_callback (source_size, source_size, progress_callback_data);
return TRUE;
}
#endif
static gboolean
file_copy_fallback (GFile *source,
GFile *destination,
@ -2919,9 +2988,6 @@ file_copy_fallback (GFile *source,
GFileInfo *info;
const char *target;
gboolean result;
#ifdef HAVE_SPLICE
gboolean fallback = TRUE;
#endif
/* need to know the file type */
info = g_file_query_info (source,
@ -2988,6 +3054,26 @@ file_copy_fallback (GFile *source,
return FALSE;
}
#ifdef HAVE_SYS_IOCTL_H
if (G_IS_FILE_DESCRIPTOR_BASED (in) && G_IS_FILE_DESCRIPTOR_BASED (out))
{
GError *reflink_err = NULL;
result = btrfs_reflink_with_progress (in, out, info, cancellable,
progress_callback, progress_callback_data,
&reflink_err);
if (result || !g_error_matches (reflink_err, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED))
{
if (!result)
g_propagate_error (error, reflink_err);
goto cleanup;
}
else
g_clear_error (&reflink_err);
}
#endif
#ifdef HAVE_SPLICE
if (G_IS_FILE_DESCRIPTOR_BASED (in) && G_IS_FILE_DESCRIPTOR_BASED (out))
{
@ -2999,20 +3085,20 @@ file_copy_fallback (GFile *source,
if (result || !g_error_matches (splice_err, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED))
{
fallback = FALSE;
if (!result)
g_propagate_error (error, splice_err);
goto cleanup;
}
else
g_clear_error (&splice_err);
}
if (fallback)
#endif
result = copy_stream_with_progress (in, out, source, cancellable,
progress_callback, progress_callback_data,
error);
result = copy_stream_with_progress (in, out, source, cancellable,
progress_callback, progress_callback_data,
error);
cleanup:
/* Don't care about errors in source here */
g_input_stream_close (in, cancellable, NULL);
@ -3026,7 +3112,7 @@ file_copy_fallback (GFile *source,
if (result == FALSE)
return FALSE;
copied_file:
copied_file:
/* Ignore errors here. Failure to copy metadata is not a hard error */
g_file_copy_attributes (source, destination,
flags, cancellable, NULL);