btrfs: do not BUG_ON after failure to migrate space during truncation

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During truncation we reserve 2 metadata units when starting a transaction
(reserved space goes to fs_info->trans_block_rsv) and then attempt to
migrate 1 unit (min_size bytes) from fs_info->trans_block_rsv into the
local block reserve. If we ever fail we trigger a BUG_ON(), which should
never happen, because we reserved 2 units. However if we happen to fail
for some reason, we don't need to be so dire and hit a BUG_ON(), we can
just error out the truncation and, since this is highly unexpected,
surround the error check with WARN_ON(), to get an informative stack
trace and tag the branh as 'unlikely'. Also make the 'min_size' variable
const, since it's not supposed to ever change and any accidental change
could possibly make the space migration not so unlikely to fail.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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Filipe Manana 2023-06-13 17:07:54 +01:00 • committed by David Sterba

parent df9f278239

commit 6822b3f708

1 changed files with 18 additions and 3 deletions

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fs/btrfs/inode.c

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