From: Al Viro <viro@zeniv.linux.org.uk>
To: Eric Biggers <ebiggers@kernel.org>
Cc: linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-ext4@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [PATCH] fscrypt: cache decrypted symlink target in ->i_link
Date: Wed, 10 Apr 2019 04:44:14 +0100 [thread overview]
Message-ID: <20190410034414.GW2217@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20190410025808.GA7140@sol.localdomain>
On Tue, Apr 09, 2019 at 07:58:08PM -0700, Eric Biggers wrote:
> It could check a flag IOP_GET_LINK in ->i_opflags instead, so it would be the
> same number of checks. See patch below.
With that patch ->i_link is completely unused if ->get_link() is non-NULL,
so you get a method call on each traversal...
> Benefits are that we get code that isn't actively misleading (via
> simple_get_link() existing but actually never being called), and filesystems can
> cache a symlink target in ->i_link if it becomes available later, i.e. if it's
> not immediately available at iget() time. Otherwise a filesystem-private field
> has to be used instead. (For fscrypt, I'd probably use fscrypt_info::ci_link.)
What's to stop you from doing just that right now? You'd need to take
care with barriers, but you'd need that anyway... As soon as ->i_link is set
you'll get no more ->get_link() on that sucker, using the cached value
from that point on. IDGI...
WARNING: multiple messages have this Message-ID (diff)
From: Al Viro <viro@zeniv.linux.org.uk>
To: Eric Biggers <ebiggers@kernel.org>
Cc: linux-fsdevel@vger.kernel.org, linux-fscrypt@vger.kernel.org,
linux-ext4@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [PATCH] fscrypt: cache decrypted symlink target in ->i_link
Date: Wed, 10 Apr 2019 04:44:14 +0100 [thread overview]
Message-ID: <20190410034414.GW2217@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20190410025808.GA7140@sol.localdomain>
On Tue, Apr 09, 2019 at 07:58:08PM -0700, Eric Biggers wrote:
> It could check a flag IOP_GET_LINK in ->i_opflags instead, so it would be the
> same number of checks. See patch below.
With that patch ->i_link is completely unused if ->get_link() is non-NULL,
so you get a method call on each traversal...
> Benefits are that we get code that isn't actively misleading (via
> simple_get_link() existing but actually never being called), and filesystems can
> cache a symlink target in ->i_link if it becomes available later, i.e. if it's
> not immediately available at iget() time. Otherwise a filesystem-private field
> has to be used instead. (For fscrypt, I'd probably use fscrypt_info::ci_link.)
What's to stop you from doing just that right now? You'd need to take
care with barriers, but you'd need that anyway... As soon as ->i_link is set
you'll get no more ->get_link() on that sucker, using the cached value
from that point on. IDGI...
next prev parent reply other threads:[~2019-04-10 3:44 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-09 23:35 [PATCH] fscrypt: cache decrypted symlink target in ->i_link Eric Biggers
2019-04-09 23:35 ` [f2fs-dev] " Eric Biggers
2019-04-10 0:33 ` Al Viro
2019-04-10 0:33 ` Al Viro
2019-04-10 0:45 ` Eric Biggers
2019-04-10 0:45 ` Eric Biggers
2019-04-10 1:04 ` Al Viro
2019-04-10 1:04 ` Al Viro
2019-04-10 1:22 ` Eric Biggers
2019-04-10 1:22 ` [f2fs-dev] " Eric Biggers
2019-04-10 1:22 ` Eric Biggers
2019-04-10 1:39 ` Al Viro
2019-04-10 1:39 ` Al Viro
2019-04-10 2:58 ` Eric Biggers
2019-04-10 2:58 ` Eric Biggers
2019-04-10 3:44 ` Al Viro [this message]
2019-04-10 3:44 ` Al Viro
2019-04-10 4:04 ` Eric Biggers
2019-04-10 4:04 ` [f2fs-dev] " Eric Biggers
2019-04-10 4:04 ` Eric Biggers
2019-04-10 4:16 ` Eric Biggers
2019-04-10 4:31 ` Al Viro
2019-04-10 4:31 ` Al Viro
2019-04-10 5:04 ` Eric Biggers
2019-04-10 5:04 ` [f2fs-dev] " Eric Biggers
2019-04-10 5:04 ` Eric Biggers
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