ext4: remove unnecessary comments in ext4_orphan_add() (afb86178) · Commits · 戴 / test

The comment from Al Viro about possible race in the ext4_orphan_add() is not justified. There is no race possible as we always have either i_mutex locked, or the inode can not be referenced from outside hence the J_ASSERS should not be hit from the reason described in comment. This commit replaces it with notion that we are holding i_mutex so it should not be possible for i_nlink to be changed while waiting for s_orphan_lock. Signed-off-by:

Lukas Czerner <lczerner@redhat.com> Signed-off-by:

"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/namei.c

+5 −12

Original line number	Diff line number	Diff line
		@@ -1989,18 +1989,11 @@ int ext4_orphan_add(handle_t handle, struct inode inode)
		if (!list_empty(&EXT4_I(inode)->i_orphan))
		goto out_unlock;

		/* Orphan handling is only valid for files with data blocks
		* being truncated, or files being unlinked. */

		/* @@@ FIXME: Observation from aviro:
		* I think I can trigger J_ASSERT in ext4_orphan_add(). We block
		* here (on s_orphan_lock), so race with ext4_link() which might bump
		* ->i_nlink. For, say it, character device. Not a regular file,
		* not a directory, not a symlink and ->i_nlink > 0.
		*
		* tytso, 4/25/2009: I'm not sure how that could happen;
		* shouldn't the fs core protect us from these sort of
		* unlink()/link() races?
		/*
		* Orphan handling is only valid for files with data blocks
		* being truncated, or files being unlinked. Note that we either
		* hold i_mutex, or the inode can not be referenced from outside,
		* so i_nlink should not be bumped due to race
		*/
		J_ASSERT((S_ISREG(inode->i_mode) \|\| S_ISDIR(inode->i_mode) \|\|
		S_ISLNK(inode->i_mode)) \|\| inode->i_nlink == 0);

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