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Message-ID: <63ec62b9a1285_18bf5929449@iweiny-mobl.notmuch>
Date: Tue, 14 Feb 2023 20:42:33 -0800
From: Ira Weiny <ira.weiny@...el.com>
To: "Fabio M. De Francesco" <fmdefrancesco@...il.com>,
Tyler Hicks <code@...icks.com>,
"Matthew Wilcox (Oracle)" <willy@...radead.org>,
Christian Brauner <brauner@...nel.org>,
Damien Le Moal <damien.lemoal@...nsource.wdc.com>,
Al Viro <viro@...iv.linux.org.uk>,
"Muchun Song" <muchun.song@...ux.dev>, <ecryptfs@...r.kernel.org>,
<linux-kernel@...r.kernel.org>
CC: Ira Weiny <ira.weiny@...el.com>
Subject: Re: [PATCH] fs/ecryptfs: Replace kmap_atomic() with kmap_local_page()
Fabio M. De Francesco wrote:
> kmap_atomic() is deprecated in favor of kmap_local_page(). Therefore,
> replace kmap_atomic() with kmap_local_page() in ecryptfs_write().
>
> kmap_atomic() is implemented like a kmap_local_page() which also disables
> page-faults and preemption (the latter only for !PREEMPT_RT kernels).
>
> The code within the mapping/un-mapping in ecryptfs_write() does not
> depend on the above-mentioned side effects.
>
> Therefore, a mere replacement of the old API with the new one is all that
> is required (i.e., there is no need to explicitly add any calls to
> pagefault_disable() and/or preempt_disable()).
>
> Suggested-by: Ira Weiny <ira.weiny@...el.com>
Reviewed-by: Ira Weiny <ira.weiny@...el.com>
> Signed-off-by: Fabio M. De Francesco <fmdefrancesco@...il.com>
> ---
> fs/ecryptfs/read_write.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ecryptfs/read_write.c b/fs/ecryptfs/read_write.c
> index 5edf027c8359..3458f153a588 100644
> --- a/fs/ecryptfs/read_write.c
> +++ b/fs/ecryptfs/read_write.c
> @@ -140,7 +140,7 @@ int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset,
> ecryptfs_page_idx, rc);
> goto out;
> }
> - ecryptfs_page_virt = kmap_atomic(ecryptfs_page);
> + ecryptfs_page_virt = kmap_local_page(ecryptfs_page);
>
> /*
> * pos: where we're now writing, offset: where the request was
> @@ -163,7 +163,7 @@ int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset,
> (data + data_offset), num_bytes);
> data_offset += num_bytes;
> }
> - kunmap_atomic(ecryptfs_page_virt);
> + kunmap_local(ecryptfs_page_virt);
> flush_dcache_page(ecryptfs_page);
> SetPageUptodate(ecryptfs_page);
> unlock_page(ecryptfs_page);
> --
> 2.39.0
>
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