From 5eba9784979e0b723c05a45cf767046607e4e759 Mon Sep 17 00:00:00 2001 From: Nirbheek Chauhan Date: Sat, 5 Jan 2013 12:52:31 +0530 Subject: [PATCH] GFile: Add Btrfs clone ioctl support 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 --- configure.ac | 1 + gio/gfile.c | 104 ++++++++++++++++++++++++++++++++++++++++++++++----- 2 files changed, 96 insertions(+), 9 deletions(-) diff --git a/configure.ac b/configure.ac index 30e9a4d1b..40760f2fe 100644 --- a/configure.ac +++ b/configure.ac @@ -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 diff --git a/gio/gfile.c b/gio/gfile.c index cd02b66e6..3a0e94765 100644 --- a/gio/gfile.c +++ b/gio/gfile.c @@ -23,17 +23,28 @@ */ #include "config.h" + +#if HAVE_SYS_IOCTL_H +#include +#include +/* 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 #include #include #include #endif + #include #include #ifdef HAVE_PWD_H #include #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);