kernfs: Skip kernfs_drain_open_files() more aggressively

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Track the number of mmapped files and files that need to be released and
skip kernfs_drain_open_file() if both are zero, which are the precise
conditions which require draining open_files. The early exit test is
factored into kernfs_should_drain_open_files() which is now tested by
kernfs_drain_open_files()'s caller - kernfs_drain().

This isn't a meaningful optimization on its own but will enable future
stand-alone kernfs_deactivate() implementation.

v2: Chengming noticed that on->nr_to_release was leaking after ->open()
    failure. Fix it by telling kernfs_unlink_open_file() that it's called
    from the ->open() fail path and should dec the counter. Use kzalloc() to
    allocate kernfs_open_node so that the tracking fields are correctly
    initialized.

Cc: Chengming Zhou <zhouchengming@bytedance.com>
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220828050440.734579-5-tj@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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This commit is contained in:

Tejun Heo 2022-08-27 19:04:35 -10:00 • committed by Greg Kroah-Hartman

parent cf2dc9db93

commit bdb2fd7fc5

3 changed files with 48 additions and 21 deletions

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3

fs/kernfs/dir.c

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65

fs/kernfs/file.c

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1

fs/kernfs/kernfs-internal.h

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