2024-01-30 16:55:00

by Mathieu Desnoyers

[permalink] [raw]
Subject: [RFC PATCH v2 3/8] ext2: Use dax_is_supported()

Use dax_is_supported() to validate whether the architecture has
virtually aliased data caches at mount time. Print an error and disable
DAX if dax=always is requested as a mount option on an architecture
which does not support DAX.

This is relevant for architectures which require a dynamic check
to validate whether they have virtually aliased data caches.

Fixes: d92576f1167c ("dax: does not work correctly with virtual aliasing caches")
Signed-off-by: Mathieu Desnoyers <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: [email protected]
Cc: Andrew Morton <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: Dan Williams <[email protected]>
Cc: Vishal Verma <[email protected]>
Cc: Dave Jiang <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Russell King <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
fs/ext2/super.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 01f9addc8b1f..30ff57d47ed4 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -955,7 +955,11 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);

if (test_opt(sb, DAX)) {
- if (!sbi->s_daxdev) {
+ if (!dax_is_supported()) {
+ ext2_msg(sb, KERN_ERR,
+ "DAX unsupported by architecture. Turning off DAX.");
+ clear_opt(sbi->s_mount_opt, DAX);
+ } else if (!sbi->s_daxdev) {
ext2_msg(sb, KERN_ERR,
"DAX unsupported by block device. Turning off DAX.");
clear_opt(sbi->s_mount_opt, DAX);
--
2.39.2



2024-01-30 21:40:25

by Jan Kara

[permalink] [raw]
Subject: Re: [RFC PATCH v2 3/8] ext2: Use dax_is_supported()

On Tue 30-01-24 11:52:50, Mathieu Desnoyers wrote:
> Use dax_is_supported() to validate whether the architecture has
> virtually aliased data caches at mount time. Print an error and disable
> DAX if dax=always is requested as a mount option on an architecture
> which does not support DAX.
>
> This is relevant for architectures which require a dynamic check
> to validate whether they have virtually aliased data caches.
>
> Fixes: d92576f1167c ("dax: does not work correctly with virtual aliasing caches")
> Signed-off-by: Mathieu Desnoyers <[email protected]>
> Cc: Jan Kara <[email protected]>
> Cc: [email protected]
> Cc: Andrew Morton <[email protected]>
> Cc: Linus Torvalds <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: Dan Williams <[email protected]>
> Cc: Vishal Verma <[email protected]>
> Cc: Dave Jiang <[email protected]>
> Cc: Matthew Wilcox <[email protected]>
> Cc: Arnd Bergmann <[email protected]>
> Cc: Russell King <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]

OK, yeah, this is better than v1. Feel free to add:

Acked-by: Jan Kara <[email protected]>

Honza

> ---
> fs/ext2/super.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/fs/ext2/super.c b/fs/ext2/super.c
> index 01f9addc8b1f..30ff57d47ed4 100644
> --- a/fs/ext2/super.c
> +++ b/fs/ext2/super.c
> @@ -955,7 +955,11 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
> blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
>
> if (test_opt(sb, DAX)) {
> - if (!sbi->s_daxdev) {
> + if (!dax_is_supported()) {
> + ext2_msg(sb, KERN_ERR,
> + "DAX unsupported by architecture. Turning off DAX.");
> + clear_opt(sbi->s_mount_opt, DAX);
> + } else if (!sbi->s_daxdev) {
> ext2_msg(sb, KERN_ERR,
> "DAX unsupported by block device. Turning off DAX.");
> clear_opt(sbi->s_mount_opt, DAX);
> --
> 2.39.2
>
--
Jan Kara <[email protected]>
SUSE Labs, CR