kernel/git/stable/linux.git/fs/btrfs/delalloc-space.c, branch linux-5.3.y

btrfs: qgroup: Always free PREALLOC META reserve in btrfs_delalloc_release_extents()

2019-11-06T12:07:43+00:00

[ Upstream commit 8702ba9396bf7bbae2ab93c94acd4bd37cfa4f09 ] [Background] Btrfs qgroup uses two types of reserved space for METADATA space, PERTRANS and PREALLOC. PERTRANS is metadata space reserved for each transaction started by btrfs_start_transaction(). While PREALLOC is for delalloc, where we reserve space before joining a transaction, and finally it will be converted to PERTRANS after the writeback is done. [Inconsistency] However there is inconsistency in how we handle PREALLOC metadata space. The most obvious one is: In btrfs_buffered_write(): btrfs_delalloc_release_extents(BTRFS_I(inode), reserve_bytes, true); We always free qgroup PREALLOC meta space. While in btrfs_truncate_block(): btrfs_delalloc_release_extents(BTRFS_I(inode), blocksize, (ret != 0)); We only free qgroup PREALLOC meta space when something went wrong. [The Correct Behavior] The correct behavior should be the one in btrfs_buffered_write(), we should always free PREALLOC metadata space. The reason is, the btrfs_delalloc_* mechanism works by: - Reserve metadata first, even it's not necessary In btrfs_delalloc_reserve_metadata() - Free the unused metadata space Normally in: btrfs_delalloc_release_extents() |- btrfs_inode_rsv_release() Here we do calculation on whether we should release or not. E.g. for 64K buffered write, the metadata rsv works like: /* The first page */ reserve_meta: num_bytes=calc_inode_reservations() free_meta: num_bytes=0 total: num_bytes=calc_inode_reservations() /* The first page caused one outstanding extent, thus needs metadata rsv */ /* The 2nd page */ reserve_meta: num_bytes=calc_inode_reservations() free_meta: num_bytes=calc_inode_reservations() total: not changed /* The 2nd page doesn't cause new outstanding extent, needs no new meta rsv, so we free what we have reserved */ /* The 3rd~16th pages */ reserve_meta: num_bytes=calc_inode_reservations() free_meta: num_bytes=calc_inode_reservations() total: not changed (still space for one outstanding extent) This means, if btrfs_delalloc_release_extents() determines to free some space, then those space should be freed NOW. So for qgroup, we should call btrfs_qgroup_free_meta_prealloc() other than btrfs_qgroup_convert_reserved_meta(). The good news is: - The callers are not that hot The hottest caller is in btrfs_buffered_write(), which is already fixed by commit 336a8bb8e36a ("btrfs: Fix wrong btrfs_delalloc_release_extents parameter"). Thus it's not that easy to cause false EDQUOT. - The trans commit in advance for qgroup would hide the bug Since commit f5fef4593653 ("btrfs: qgroup: Make qgroup async transaction commit more aggressive"), when btrfs qgroup metadata free space is slow, it will try to commit transaction and free the wrongly converted PERTRANS space, so it's not that easy to hit such bug. [FIX] So to fix the problem, remove the @qgroup_free parameter for btrfs_delalloc_release_extents(), and always pass true to btrfs_inode_rsv_release(). Reported-by: Filipe Manana Fixes: 43b18595d660 ("btrfs: qgroup: Use separate meta reservation type for delalloc") CC: stable@vger.kernel.org # 4.19+ Reviewed-by: Filipe Manana Signed-off-by: Qu Wenruo Signed-off-by: David Sterba Signed-off-by: Sasha Levin

Btrfs: fix qgroup double free after failure to reserve metadata for delalloc

2019-10-29T08:22:44+00:00

commit c7967fc1499beb9b70bb9d33525fb0b384af8883 upstream. If we fail to reserve metadata for delalloc operations we end up releasing the previously reserved qgroup amount twice, once explicitly under the 'out_qgroup' label by calling btrfs_qgroup_free_meta_prealloc() and once again, under label 'out_fail', by calling btrfs_inode_rsv_release() with a value of 'true' for its 'qgroup_free' argument, which results in btrfs_qgroup_free_meta_prealloc() being called again, so we end up having a double free. Also if we fail to reserve the necessary qgroup amount, we jump to the label 'out_fail', which calls btrfs_inode_rsv_release() and that in turns calls btrfs_qgroup_free_meta_prealloc(), even though we weren't able to reserve any qgroup amount. So we freed some amount we never reserved. So fix this by removing the call to btrfs_inode_rsv_release() in the failure path, since it's not necessary at all as we haven't changed the inode's block reserve in any way at this point. Fixes: c8eaeac7b73434 ("btrfs: reserve delalloc metadata differently") CC: stable@vger.kernel.org # 5.2+ Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman

btrfs: migrate the delalloc space stuff to it's own home

2019-07-04T15:26:17+00:00

We have code for data and metadata reservations for delalloc. There's quite a bit of code here, and it's used in a lot of places so I've separated it out to it's own file. inode.c and file.c are already pretty large, and this code is complicated enough to live in its own space. Signed-off-by: Josef Bacik Signed-off-by: David Sterba