kmap_atomic() is deprecated in favor of kmap_local_page(). Therefore,
replace kmap_atomic() with kmap_local_page().
kmap_atomic() is implemented like a kmap_local_page() which also disables
page-faults and preemption (the latter only for !PREEMPT_RT kernels).
However, the code within the mappings and un-mappings in ext4/inline.c
does not depend on the above-mentioned side effects.
Therefore, a mere replacement of the old API with the new one is all it
is required (i.e., there is no need to explicitly add any calls to
pagefault_disable() and/or preempt_disable()).
Suggested-by: Ira Weiny <[email protected]>
Signed-off-by: Fabio M. De Francesco <[email protected]>
---
I tried my best to understand the code within mapping and un-mapping.
However, I'm not an expert. Therefore, although I'm pretty confident, I
cannot be 100% sure that the code between the mapping and the un-mapping
does not depend on pagefault_disable() and/or preempt_disable().
Unfortunately, I cannot currently test this changes to check the
above-mentioned assumptions. However, if I'm required to do the tests
with (x)fstests, I have no problems with doing them in the next days.
If so, I'll test in a QEMU/KVM x86_32 VM, 6GB RAM, booting a kernel with
HIGHMEM64GB enabled.
I'd like to hear whether or not the maintainers require these tests
and/or other tests.
fs/ext4/inline.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index 2b42ececa46d..bfb044425d8a 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -490,10 +490,10 @@ static int ext4_read_inline_page(struct inode *inode, struct page *page)
goto out;
len = min_t(size_t, ext4_get_inline_size(inode), i_size_read(inode));
- kaddr = kmap_atomic(page);
+ kaddr = kmap_local_page(page);
ret = ext4_read_inline_data(inode, kaddr, len, &iloc);
flush_dcache_page(page);
- kunmap_atomic(kaddr);
+ kunmap_local(kaddr);
zero_user_segment(page, len, PAGE_SIZE);
SetPageUptodate(page);
brelse(iloc.bh);
@@ -763,9 +763,9 @@ int ext4_write_inline_data_end(struct inode *inode, loff_t pos, unsigned len,
*/
(void) ext4_find_inline_data_nolock(inode);
- kaddr = kmap_atomic(page);
+ kaddr = kmap_local_page(page);
ext4_write_inline_data(inode, &iloc, kaddr, pos, copied);
- kunmap_atomic(kaddr);
+ kunmap_local(kaddr);
SetPageUptodate(page);
/* clear page dirty so that writepages wouldn't work for us. */
ClearPageDirty(page);
@@ -831,9 +831,9 @@ ext4_journalled_write_inline_data(struct inode *inode,
}
ext4_write_lock_xattr(inode, &no_expand);
- kaddr = kmap_atomic(page);
+ kaddr = kmap_local_page(page);
ext4_write_inline_data(inode, &iloc, kaddr, 0, len);
- kunmap_atomic(kaddr);
+ kunmap_local(kaddr);
ext4_write_unlock_xattr(inode, &no_expand);
return iloc.bh;
--
2.39.0
On Sat 31-12-22 18:44:39, Fabio M. De Francesco wrote:
> kmap_atomic() is deprecated in favor of kmap_local_page(). Therefore,
> replace kmap_atomic() with kmap_local_page().
>
> kmap_atomic() is implemented like a kmap_local_page() which also disables
> page-faults and preemption (the latter only for !PREEMPT_RT kernels).
>
> However, the code within the mappings and un-mappings in ext4/inline.c
> does not depend on the above-mentioned side effects.
>
> Therefore, a mere replacement of the old API with the new one is all it
> is required (i.e., there is no need to explicitly add any calls to
> pagefault_disable() and/or preempt_disable()).
>
> Suggested-by: Ira Weiny <[email protected]>
> Signed-off-by: Fabio M. De Francesco <[email protected]>
The patch looks good to me. Feel free to add:
Reviewed-by: Jan Kara <[email protected]>
Honza
> ---
>
> I tried my best to understand the code within mapping and un-mapping.
> However, I'm not an expert. Therefore, although I'm pretty confident, I
> cannot be 100% sure that the code between the mapping and the un-mapping
> does not depend on pagefault_disable() and/or preempt_disable().
>
> Unfortunately, I cannot currently test this changes to check the
> above-mentioned assumptions. However, if I'm required to do the tests
> with (x)fstests, I have no problems with doing them in the next days.
>
> If so, I'll test in a QEMU/KVM x86_32 VM, 6GB RAM, booting a kernel with
> HIGHMEM64GB enabled.
>
> I'd like to hear whether or not the maintainers require these tests
> and/or other tests.
>
> fs/ext4/inline.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
> index 2b42ececa46d..bfb044425d8a 100644
> --- a/fs/ext4/inline.c
> +++ b/fs/ext4/inline.c
> @@ -490,10 +490,10 @@ static int ext4_read_inline_page(struct inode *inode, struct page *page)
> goto out;
>
> len = min_t(size_t, ext4_get_inline_size(inode), i_size_read(inode));
> - kaddr = kmap_atomic(page);
> + kaddr = kmap_local_page(page);
> ret = ext4_read_inline_data(inode, kaddr, len, &iloc);
> flush_dcache_page(page);
> - kunmap_atomic(kaddr);
> + kunmap_local(kaddr);
> zero_user_segment(page, len, PAGE_SIZE);
> SetPageUptodate(page);
> brelse(iloc.bh);
> @@ -763,9 +763,9 @@ int ext4_write_inline_data_end(struct inode *inode, loff_t pos, unsigned len,
> */
> (void) ext4_find_inline_data_nolock(inode);
>
> - kaddr = kmap_atomic(page);
> + kaddr = kmap_local_page(page);
> ext4_write_inline_data(inode, &iloc, kaddr, pos, copied);
> - kunmap_atomic(kaddr);
> + kunmap_local(kaddr);
> SetPageUptodate(page);
> /* clear page dirty so that writepages wouldn't work for us. */
> ClearPageDirty(page);
> @@ -831,9 +831,9 @@ ext4_journalled_write_inline_data(struct inode *inode,
> }
>
> ext4_write_lock_xattr(inode, &no_expand);
> - kaddr = kmap_atomic(page);
> + kaddr = kmap_local_page(page);
> ext4_write_inline_data(inode, &iloc, kaddr, 0, len);
> - kunmap_atomic(kaddr);
> + kunmap_local(kaddr);
> ext4_write_unlock_xattr(inode, &no_expand);
>
> return iloc.bh;
> --
> 2.39.0
>
--
Jan Kara <[email protected]>
SUSE Labs, CR
On Sat, Dec 31, 2022 at 06:44:39PM +0100, Fabio M. De Francesco wrote:
> kmap_atomic() is deprecated in favor of kmap_local_page(). Therefore,
> replace kmap_atomic() with kmap_local_page().
>
> kmap_atomic() is implemented like a kmap_local_page() which also disables
> page-faults and preemption (the latter only for !PREEMPT_RT kernels).
>
> However, the code within the mappings and un-mappings in ext4/inline.c
> does not depend on the above-mentioned side effects.
>
> Therefore, a mere replacement of the old API with the new one is all it
> is required (i.e., there is no need to explicitly add any calls to
> pagefault_disable() and/or preempt_disable()).
>
> Suggested-by: Ira Weiny <[email protected]>
Reviewed-by: Ira Weiny <[email protected]>
> Signed-off-by: Fabio M. De Francesco <[email protected]>
> ---
>
> I tried my best to understand the code within mapping and un-mapping.
> However, I'm not an expert. Therefore, although I'm pretty confident, I
> cannot be 100% sure that the code between the mapping and the un-mapping
> does not depend on pagefault_disable() and/or preempt_disable().
>
> Unfortunately, I cannot currently test this changes to check the
> above-mentioned assumptions. However, if I'm required to do the tests
> with (x)fstests, I have no problems with doing them in the next days.
>
> If so, I'll test in a QEMU/KVM x86_32 VM, 6GB RAM, booting a kernel with
> HIGHMEM64GB enabled.
>
> I'd like to hear whether or not the maintainers require these tests
> and/or other tests.
>
> fs/ext4/inline.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
> index 2b42ececa46d..bfb044425d8a 100644
> --- a/fs/ext4/inline.c
> +++ b/fs/ext4/inline.c
> @@ -490,10 +490,10 @@ static int ext4_read_inline_page(struct inode *inode, struct page *page)
> goto out;
>
> len = min_t(size_t, ext4_get_inline_size(inode), i_size_read(inode));
> - kaddr = kmap_atomic(page);
> + kaddr = kmap_local_page(page);
> ret = ext4_read_inline_data(inode, kaddr, len, &iloc);
> flush_dcache_page(page);
> - kunmap_atomic(kaddr);
> + kunmap_local(kaddr);
> zero_user_segment(page, len, PAGE_SIZE);
> SetPageUptodate(page);
> brelse(iloc.bh);
> @@ -763,9 +763,9 @@ int ext4_write_inline_data_end(struct inode *inode, loff_t pos, unsigned len,
> */
> (void) ext4_find_inline_data_nolock(inode);
>
> - kaddr = kmap_atomic(page);
> + kaddr = kmap_local_page(page);
> ext4_write_inline_data(inode, &iloc, kaddr, pos, copied);
> - kunmap_atomic(kaddr);
> + kunmap_local(kaddr);
> SetPageUptodate(page);
> /* clear page dirty so that writepages wouldn't work for us. */
> ClearPageDirty(page);
> @@ -831,9 +831,9 @@ ext4_journalled_write_inline_data(struct inode *inode,
> }
>
> ext4_write_lock_xattr(inode, &no_expand);
> - kaddr = kmap_atomic(page);
> + kaddr = kmap_local_page(page);
> ext4_write_inline_data(inode, &iloc, kaddr, 0, len);
> - kunmap_atomic(kaddr);
> + kunmap_local(kaddr);
> ext4_write_unlock_xattr(inode, &no_expand);
>
> return iloc.bh;
> --
> 2.39.0
>