tree 77c6d3a2925144a5221800ba687c8a816236c94c
parent 575880f2d42b7c16669f0fc9ca4ae6ed718d4b90
author Qu Wenruo <quwenruo@cn.fujitsu.com> 1498096881 +0800
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1550909159 +0100

btrfs: Remove false alert when fiemap range is smaller than on-disk extent

commit 848c23b78fafdcd3270b06a30737f8dbd70c347f upstream.

Commit 4751832da990 ("btrfs: fiemap: Cache and merge fiemap extent before
submit it to user") introduced a warning to catch unemitted cached
fiemap extent.

However such warning doesn't take the following case into consideration:

0			4K			8K
|<---- fiemap range --->|
|<----------- On-disk extent ------------------>|

In this case, the whole 0~8K is cached, and since it's larger than
fiemap range, it break the fiemap extent emit loop.
This leaves the fiemap extent cached but not emitted, and caught by the
final fiemap extent sanity check, causing kernel warning.

This patch removes the kernel warning and renames the sanity check to
emit_last_fiemap_cache() since it's possible and valid to have cached
fiemap extent.

Reported-by: David Sterba <dsterba@suse.cz>
Reported-by: Adam Borowski <kilobyte@angband.pl>
Fixes: 4751832da990 ("btrfs: fiemap: Cache and merge fiemap extent ...")
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>