Patchset to solve the previous found freeze/sysfs deadlock.
Unlike previous pending_changes, which uses transaction commits to
ensure mount option doesn't change during transaction.
This idea is great in concept, but will introduce extra and somewhat
duplicated ro/freeze check, and the original synchronized behavior is
also changed.
[Per-transaction mount option]
This patch use the RCU-like concept, which will copy the mount_opt from
fs_info into btrfs_transaction, and each btrfs_test_opt() for specific
mount option bit(SPACE_CACHE/INODE_MAP_CACHE) should be changed to
btrfs_test_trans_opt().
So mount option during transaction won't be changed, and also, no extra
read_only or freeze check is needed, the commit routine is also
untouched.
[Use VFS protect for sysfs change]
The 6th patch will introduce a new help function get_vfsmount_sb() to
get a vfsmount from a sb, with this vfsmount, we can use vfs level
mnt_want_write() to do a comprehensive protection other than the cheap
ro/freeze check.
Changelog:
v1:
Only use cheap freeze check to avoid deadlock.
v2:
Fix the never changed pending_changes bug and handle transaction in
btrfs_freeze()
v3:
Add atomic mount option change and per-trans mount option.
v4:
Add mnt_want_write() in sysfs handler.
Qu Wenruo (8):
Revert "btrfs: add support for processing pending changes" related
commits
btrfs: Make btrfs_parse_options() parse mount option in a atomic way
btrfs: Introduce per-transaction mount_opt to keep mount option
consistent during transaction.
btrfs: Use btrfs_test_trans_opt() to handle SPACE_CACHE if it's under
transaction protect.
btrfs: Use btrfs_test_trans_opt() to handle INODE_CACHE if it's under
transaction protect.
vfs: Add get_vfsmount_sb() function to get vfsmount from a given sb.
btrfs: Use mnt_want_write() to protect label change.
btrfs: Use mnt_want_write() to protect sysfs feature change.
fs/btrfs/ctree.h | 64 +++-------------------
fs/btrfs/disk-io.c | 6 ---
fs/btrfs/extent-tree.c | 2 +-
fs/btrfs/free-space-cache.c | 2 +-
fs/btrfs/inode-map.c | 5 +-
fs/btrfs/super.c | 129 ++++++++++++++++++++++----------------------
fs/btrfs/sysfs.c | 73 ++++++++++++++++++-------
fs/btrfs/transaction.c | 43 ++-------------
fs/btrfs/transaction.h | 6 ++-
fs/namespace.c | 25 +++++++++
include/linux/mount.h | 1 +
11 files changed, 167 insertions(+), 189 deletions(-)
--
2.2.2
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
