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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,
	linux-mtd@lists.infradead.org
Subject: Re: [PATCH v2 1/2] vfs: use READ_ONCE() to access ->i_link
Date: Wed, 10 Apr 2019 22:06:57 +0100	[thread overview]
Message-ID: <20190410210657.GA2217@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20190410202115.64501-2-ebiggers@kernel.org>

On Wed, Apr 10, 2019 at 01:21:14PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> Use 'READ_ONCE(inode->i_link)' to explicitly support filesystems caching
> the symlink target in ->i_link later if it was unavailable at iget()
> time, or wasn't easily available.  I'll be doing this in fscrypt, to
> improve the performance of encrypted symlinks on ext4, f2fs, and ubifs.
> 
> ->i_link will start NULL and may later be set to a non-NULL value by a
> smp_store_release() or cmpxchg_release().  READ_ONCE() is needed on the
> read side.  smp_load_acquire() is unnecessary because only a data
> dependency barrier is required.  (Thanks to Al for pointing this out.)

You've missed vfs_readlink()...

  reply	other threads:[~2019-04-10 21:07 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-10 20:21 [PATCH v2 0/2] fscrypt: improve encrypted symlink performance Eric Biggers
2019-04-10 20:21 ` [PATCH v2 1/2] vfs: use READ_ONCE() to access ->i_link Eric Biggers
2019-04-10 21:06   ` Al Viro [this message]
2019-04-10 23:15     ` Eric Biggers
2019-04-11  2:25       ` Al Viro
2019-04-11 17:28         ` Eric Biggers
2019-04-17 16:41         ` Theodore Ts'o
2019-04-10 20:21 ` [PATCH v2 2/2] fscrypt: cache decrypted symlink target in ->i_link Eric Biggers
2019-04-17 16:55   ` Theodore Ts'o

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