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Btrfs: change how we update the global block rsv 

I'm writing a tool to visualize the enospc system in order to help debug enospc
bugs and I found weird data and ran it down to when we update the global block
rsv.  We add all of the remaining free space to the block rsv, do a trace event,
then remove the extra and do another trace event.  This makes my visualization
look silly and is unintuitive code as well.  Fix this stuff to only add the
amount we are missing, or free the amount we are missing.  This is less clean to
read but more explicit in what it is doing, as well as only emitting events for
values that make sense.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Josef Bacik 2016-01-11 17:28:38 -05:00 committed by David Sterba
parent 388f7b1d6e
commit fb4b10e5d5
1 changed files with 20 additions and 14 deletions
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34
fs/btrfs/extent-tree.c
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@ -5373,27 +5373,33 @@ static void update_global_block_rsv(struct btrfs_fs_info *fs_info)
block_rsv->size = min_t(u64, num_bytes, SZ_512M);
num_bytes = sinfo->bytes_used + sinfo->bytes_pinned +
sinfo->bytes_reserved + sinfo->bytes_readonly +
sinfo->bytes_may_use;
if (sinfo->total_bytes > num_bytes) {
num_bytes = sinfo->total_bytes - num_bytes;
block_rsv->reserved += num_bytes;
sinfo->bytes_may_use += num_bytes;
trace_btrfs_space_reservation(fs_info, "space_info",
sinfo->flags, num_bytes, 1);
}
if (block_rsv->reserved >= block_rsv->size) {
if (block_rsv->reserved < block_rsv->size) {
num_bytes = sinfo->bytes_used + sinfo->bytes_pinned +
sinfo->bytes_reserved + sinfo->bytes_readonly +
sinfo->bytes_may_use;
if (sinfo->total_bytes > num_bytes) {
num_bytes = sinfo->total_bytes - num_bytes;
num_bytes = min(num_bytes,
block_rsv->size - block_rsv->reserved);
block_rsv->reserved += num_bytes;
sinfo->bytes_may_use += num_bytes;
trace_btrfs_space_reservation(fs_info, "space_info",
sinfo->flags, num_bytes,
1);
}
} else if (block_rsv->reserved > block_rsv->size) {
num_bytes = block_rsv->reserved - block_rsv->size;
sinfo->bytes_may_use -= num_bytes;
trace_btrfs_space_reservation(fs_info, "space_info",
sinfo->flags, num_bytes, 0);
block_rsv->reserved = block_rsv->size;
block_rsv->full = 1;
}
if (block_rsv->reserved == block_rsv->size)
block_rsv->full = 1;
else
block_rsv->full = 0;
spin_unlock(&block_rsv->lock);
spin_unlock(&sinfo->lock);
}