btrfs: free the allocated memory if btrfs_alloc_page_array() fails

btrfs: free the allocated memory if btrfs_alloc_page_array() fails

commit 94dbf7c0871f7ae6349ba4b0341ce8f5f98a071d upstream.

[BUG]
If btrfs_alloc_page_array() fail to allocate all pages but part of the
slots, then the partially allocated pages would be leaked in function
btrfs_submit_compressed_read().

[CAUSE]
As explicitly stated, if btrfs_alloc_page_array() returned -ENOMEM,
caller is responsible to free the partially allocated pages.

For the existing call sites, most of them are fine:

- btrfs_raid_bio::stripe_pages
  Handled by free_raid_bio().

- extent_buffer::pages[]
  Handled btrfs_release_extent_buffer_pages().

- scrub_stripe::pages[]
  Handled by release_scrub_stripe().

But there is one exception in btrfs_submit_compressed_read(), if
btrfs_alloc_page_array() failed, we didn't cleanup the array and freed
the array pointer directly.

Initially there is still the error handling in commit dd137dd1f2d7
("btrfs: factor out allocating an array of pages"), but later in commit
544fe4a903ce ("btrfs: embed a btrfs_bio into struct compressed_bio"),
the error handling is removed, leading to the possible memory leak.

[FIX]
This patch would add back the error handling first, then to prevent such
situation from happening again, also
Make btrfs_alloc_page_array() to free the allocated pages as a extra
safety net, then we don't need to add the error handling to
btrfs_submit_compressed_read().

Fixes: 544fe4a903ce ("btrfs: embed a btrfs_bio into struct compressed_bio")
CC: stable@vger.kernel.org # 6.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>