Btrfs: don't consider the missing device when allocating new chunks (95669976) · Commits · 戴 / test

The original code allocated new chunks by the number of the writable devices and missing devices to make sure that any RAID levels on a degraded FS continue to be honored, but it introduced a problem that it stopped us to allocating new chunks, the steps to reproduce is following: # mkfs.btrfs -m raid1 -d raid1 -f <dev0> <dev1> # mkfs.btrfs -f <dev1> //Removing <dev1> from the original fs # mount -o degraded <dev0> <mnt> # dd if=/dev/null of=<mnt>/tmpfile bs=1M It is because we allocate new chunks only on the writable devices, if we take the number of missing devices into account, and want to allocate new chunks with higher RAID level, we will fail becaue we don't have enough writable device. Fix it by ignoring the number of missing devices when allocating new chunks. Signed-off-by:

Miao Xie <miaox@cn.fujitsu.com> Signed-off-by:

Chris Mason <clm@fb.com>

fs/btrfs/extent-tree.c

+2 −14

Original line number	Diff line number	Diff line
		@@ -3586,13 +3586,7 @@ static u64 get_restripe_target(struct btrfs_fs_info *fs_info, u64 flags)
		*/
		static u64 btrfs_reduce_alloc_profile(struct btrfs_root *root, u64 flags)
		{
		/*
		* we add in the count of missing devices because we want
		* to make sure that any RAID levels on a degraded FS
		* continue to be honored.
		*/
		u64 num_devices = root->fs_info->fs_devices->rw_devices +
		root->fs_info->fs_devices->missing_devices;
		u64 num_devices = root->fs_info->fs_devices->rw_devices;
		u64 target;
		u64 tmp;

		@@ -8440,13 +8434,7 @@ static u64 update_block_group_flags(struct btrfs_root *root, u64 flags)
		if (stripped)
		return extended_to_chunk(stripped);

		/*
		* we add in the count of missing devices because we want
		* to make sure that any RAID levels on a degraded FS
		* continue to be honored.
		*/
		num_devices = root->fs_info->fs_devices->rw_devices +
		root->fs_info->fs_devices->missing_devices;
		num_devices = root->fs_info->fs_devices->rw_devices;

		stripped = BTRFS_BLOCK_GROUP_RAID0 \|
		BTRFS_BLOCK_GROUP_RAID5 \| BTRFS_BLOCK_GROUP_RAID6 \|

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