[PATCH v2 1/2] vfs: use READ_ONCE() to access ->i_link

Al Viro viro at zeniv.linux.org.uk
Wed Apr 10 14:06:57 PDT 2019


On Wed, Apr 10, 2019 at 01:21:14PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers at 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()...



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