GGLinnk/bees
1
0
Fork 0
mirror of https://github.com/Zygo/bees.git synced 2025-05-17 21:35:45 +02:00
Code Packages

fs: do not emulate extent-same by clone

Browse Source 
It is not possible to emulate extent-same by clone in a safe way.
EXTENT_SAME has been supported in btrfs since kernel 3.13, which
is much too old to contemplate running bees on.

Remove this dangerous and unused function.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>
This commit is contained in:
Zygo Blaxell 2019-06-10 22:06:44 -04:00
parent e3747320cf
commit 87e8a21c41
2 changed files with 0 additions and 50 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
include/crucible/fs.h
View File

@ -39,11 +39,6 @@ namespace crucible {
vector<BtrfsExtentInfo> m_info; vector<BtrfsExtentInfo> m_info;
}; };
struct BtrfsExtentSameByClone : public BtrfsExtentSame {
using BtrfsExtentSame::BtrfsExtentSame;
void do_ioctl() override;
};
ostream & operator<<(ostream &os, const btrfs_ioctl_same_extent_info *info); ostream & operator<<(ostream &os, const btrfs_ioctl_same_extent_info *info);
ostream & operator<<(ostream &os, const btrfs_ioctl_same_args *info); ostream & operator<<(ostream &os, const btrfs_ioctl_same_args *info);
ostream & operator<<(ostream &os, const BtrfsExtentSame &bes); ostream & operator<<(ostream &os, const BtrfsExtentSame &bes);

45
lib/fs.cc
View File

@ -136,51 +136,6 @@ namespace crucible {
DIE_IF_MINUS_ONE(ioctl(dst_fd, BTRFS_IOC_CLONE_RANGE, &args)); DIE_IF_MINUS_ONE(ioctl(dst_fd, BTRFS_IOC_CLONE_RANGE, &args));
} }
// Userspace emulation of extent-same ioctl to work around kernel bugs
// (a memory leak, a deadlock, inability to cope with unaligned EOF, and a length limit)
// The emulation is incomplete: no locking, and we always change ctime
void
BtrfsExtentSameByClone::do_ioctl()
{
if (length <= 0) {
throw out_of_range(string("length = 0 in ") + __PRETTY_FUNCTION__);
}
vector<char> cmp_buf_common(length);
vector<char> cmp_buf_iter(length);
pread_or_die(m_fd, cmp_buf_common.data(), length, logical_offset);
for (auto i = m_info.begin(); i != m_info.end(); ++i) {
i->status = -EIO;
i->bytes_deduped = 0;
// save atime/ctime for later
Stat target_stat(i->fd);
pread_or_die(i->fd, cmp_buf_iter.data(), length, i->logical_offset);
if (cmp_buf_common == cmp_buf_iter) {
// This never happens, so stop checking.
// assert(!memcmp(cmp_buf_common.data(), cmp_buf_iter.data(), length));
btrfs_clone_range(m_fd, logical_offset, length, i->fd, i->logical_offset);
i->status = 0;
i->bytes_deduped = length;
// The extent-same ioctl does not change mtime (as of patch v4)
struct timespec restore_ts[2] = {
target_stat.st_atim,
target_stat.st_mtim
};
// Ignore futimens failure as the real extent-same ioctl would never raise it
futimens(i->fd, restore_ts);
} else {
assert(memcmp(cmp_buf_common.data(), cmp_buf_iter.data(), length));
i->status = BTRFS_SAME_DATA_DIFFERS;
}
}
}
void void
BtrfsExtentSame::do_ioctl() BtrfsExtentSame::do_ioctl()
{ {