Re: [PATCH] ext4: compensate ea_inode refs and free block on new xattr block write error

Sashiko's reviews on these threads have been genuinely useful — the
ea_inode refcount leak that this patch follows up on was its find.  This
one, though, is a false positive: mb_cache_entry_delete_or_get() and
mb_cache_entry_wait_unused() have been defined in fs/mbcache.c and
declared in include/linux/mbcache.h since commit 3dc96bba65f5 ("mbcache:
add functions to delete entry if unused", 2022), CONFIG_FS_MBCACHE is
selected by every EXT4 configuration, and fs/ext4/xattr.c already calls
mb_cache_entry_delete_or_get() at three sites before this patch — a tree
missing the symbols could not build ext4 at all.  The patch compiles,
and the fault-injection measurements in the commit message ran on a
built kernel.