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

context: workaround to prevent LOGICAL_INO and btrfs balance from running concurrently

Browse Source 
This avoids some kernel bugs.  One of them is fixed in 5.3.4 and later:

	efad8a853a "Btrfs: fix use-after-free when using the tree modification log"

There are apparently others in current kernels, so for now just put bees
on pause until the balance is done.

At some point we may want to provide an option to disable this
workaround; however, running bees and balance at the same time makes
neither particularly fast, so maybe we'll just leave it this way.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>
This commit is contained in:
Zygo Blaxell 2019-11-19 16:01:31 -05:00 committed by Kai Krakow
parent 6e75857d71
commit ac53e50d3e
2 changed files with 35 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
src/bees-context.cc
View File

@ -773,11 +773,42 @@ BeesResolveAddrResult::BeesResolveAddrResult()
{
}
void
BeesContext::wait_for_balance()
{
Timer balance_timer;
BEESNOTE("WORKAROUND: waiting for balance to stop");
while (true) {
btrfs_ioctl_balance_args args;
memset_zero<btrfs_ioctl_balance_args>(&args);
const int ret = ioctl(root_fd(), BTRFS_IOC_BALANCE_PROGRESS, &args);
if (ret < 0) {
// Either can't get balance status or not running, exit either way
break;
}
if (!(args.state & BTRFS_BALANCE_STATE_RUNNING)) {
// Balance not running, doesn't matter if paused or cancelled
break;
}
BEESLOGDEBUG("WORKAROUND: Waiting " << balance_timer << "s for balance to stop");
sleep(BEES_BALANCE_POLL_INTERVAL);
}
}
BeesResolveAddrResult
BeesContext::resolve_addr_uncached(BeesAddress addr)
{
THROW_CHECK1(invalid_argument, addr, !addr.is_magic());
THROW_CHECK0(invalid_argument, !!root_fd());
// Is there a bug where resolve and balance cause a crash (BUG_ON at fs/btrfs/ctree.c:1227)?
// Apparently yes, and more than one.
// Wait for the balance to finish before we run LOGICAL_INO
wait_for_balance();
// Time how long this takes
Timer resolve_timer;
// There is no performance benefit if we restrict the buffer size.

4
src/bees.h
View File

@ -117,6 +117,9 @@ const size_t BEES_TRANSID_FACTOR = 10;
// The actual limit in LOGICAL_INO seems to be 2730, but let's leave a little headroom
const size_t BEES_MAX_EXTENT_REF_COUNT = 2560;
// Wait this long for a balance to stop
const double BEES_BALANCE_POLL_INTERVAL = 60.0;
// Flags
const int FLAGS_OPEN_COMMON = O_NOFOLLOW | O_NONBLOCK | O_CLOEXEC | O_NOATIME | O_LARGEFILE | O_NOCTTY;
const int FLAGS_OPEN_DIR = FLAGS_OPEN_COMMON | O_RDONLY | O_DIRECTORY;
@ -716,6 +719,7 @@ class BeesContext : public enable_shared_from_this<BeesContext> {
void set_root_fd(Fd fd);
BeesResolveAddrResult resolve_addr_uncached(BeesAddress addr);
void wait_for_balance();
BeesFileRange scan_one_extent(const BeesFileRange &bfr, const Extent &e);
void rewrite_file_range(const BeesFileRange &bfr);