| Message ID | 20221231174205.8492-1-fmdefrancesco@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | fs/ext2: Replace kmap_atomic() with kmap_local_page() | expand |
On Sat 31-12-22 18:42:05, 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 mapping and un-mapping in ext2_make_empty() > 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 <ira.weiny@intel.com> > Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com> Thanks, the patch looks good and I'll queue it in my tree. I'm not sure why it got missed during the initial conversion by Ira :). 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/ext2/dir.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c > index e5cbc27ba459..0f144c5c7861 100644 > --- a/fs/ext2/dir.c > +++ b/fs/ext2/dir.c > @@ -646,7 +646,7 @@ int ext2_make_empty(struct inode *inode, struct inode *parent) > unlock_page(page); > goto fail; > } > - kaddr = kmap_atomic(page); > + kaddr = kmap_local_page(page); > memset(kaddr, 0, chunk_size); > de = (struct ext2_dir_entry_2 *)kaddr; > de->name_len = 1; > @@ -661,7 +661,7 @@ int ext2_make_empty(struct inode *inode, struct inode *parent) > de->inode = cpu_to_le32(parent->i_ino); > memcpy (de->name, "..\0", 4); > ext2_set_de_type (de, inode); > - kunmap_atomic(kaddr); > + kunmap_local(kaddr); > ext2_commit_chunk(page, 0, chunk_size); > err = ext2_handle_dirsync(inode); > fail: > -- > 2.39.0 >
On Mon, Jan 02, 2023 at 01:34:11PM +0100, Jan Kara wrote: > On Sat 31-12-22 18:42:05, 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 mapping and un-mapping in ext2_make_empty() > > 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 <ira.weiny@intel.com> > > Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com> > > Thanks, the patch looks good and I'll queue it in my tree. I'm not sure why > it got missed during the initial conversion by Ira :). > I could claim something smart like I was focused on kmap() calls only. But let's just call it laziness. ;-) LGTM Reviewed-by: Ira Weiny <ira.weiny@intel.com> > 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/ext2/dir.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c > > index e5cbc27ba459..0f144c5c7861 100644 > > --- a/fs/ext2/dir.c > > +++ b/fs/ext2/dir.c > > @@ -646,7 +646,7 @@ int ext2_make_empty(struct inode *inode, struct inode *parent) > > unlock_page(page); > > goto fail; > > } > > - kaddr = kmap_atomic(page); > > + kaddr = kmap_local_page(page); > > memset(kaddr, 0, chunk_size); > > de = (struct ext2_dir_entry_2 *)kaddr; > > de->name_len = 1; > > @@ -661,7 +661,7 @@ int ext2_make_empty(struct inode *inode, struct inode *parent) > > de->inode = cpu_to_le32(parent->i_ino); > > memcpy (de->name, "..\0", 4); > > ext2_set_de_type (de, inode); > > - kunmap_atomic(kaddr); > > + kunmap_local(kaddr); > > ext2_commit_chunk(page, 0, chunk_size); > > err = ext2_handle_dirsync(inode); > > fail: > > -- > > 2.39.0 > > > -- > Jan Kara <jack@suse.com> > SUSE Labs, CR
diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c index e5cbc27ba459..0f144c5c7861 100644 --- a/fs/ext2/dir.c +++ b/fs/ext2/dir.c @@ -646,7 +646,7 @@ int ext2_make_empty(struct inode *inode, struct inode *parent) unlock_page(page); goto fail; } - kaddr = kmap_atomic(page); + kaddr = kmap_local_page(page); memset(kaddr, 0, chunk_size); de = (struct ext2_dir_entry_2 *)kaddr; de->name_len = 1; @@ -661,7 +661,7 @@ int ext2_make_empty(struct inode *inode, struct inode *parent) de->inode = cpu_to_le32(parent->i_ino); memcpy (de->name, "..\0", 4); ext2_set_de_type (de, inode); - kunmap_atomic(kaddr); + kunmap_local(kaddr); ext2_commit_chunk(page, 0, chunk_size); err = ext2_handle_dirsync(inode); fail:
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 mapping and un-mapping in ext2_make_empty() 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 <ira.weiny@intel.com> Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com> --- 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/ext2/dir.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)