linux.git/fs, branch v4.10-rc2

ext4: Simplify DAX fault path

2016-12-27T04:29:25+00:00

Now that dax_iomap_fault() calls ->iomap_begin() without entry lock, we
can use transaction starting in ext4_iomap_begin() and thus simplify
ext4_dax_fault(). It also provides us proper retries in case of ENOSPC.

Signed-off-by: Jan Kara 
Signed-off-by: Dan Williams

dax: Call ->iomap_begin without entry lock during dax fault

2016-12-27T04:29:25+00:00

Currently ->iomap_begin() handler is called with entry lock held. If the
filesystem held any locks between ->iomap_begin() and ->iomap_end()
(such as ext4 which will want to hold transaction open), this would cause
lock inversion with the iomap_apply() from standard IO path which first
calls ->iomap_begin() and only then calls ->actor() callback which grabs
entry locks for DAX (if it faults when copying from/to user provided
buffers).

Fix the problem by nesting grabbing of entry lock inside ->iomap_begin()
- ->iomap_end() pair.

Reviewed-by: Ross Zwisler 
Signed-off-by: Jan Kara 
Signed-off-by: Dan Williams

dax: Finish fault completely when loading holes

2016-12-27T04:29:25+00:00

The only case when we do not finish the page fault completely is when we
are loading hole pages into a radix tree. Avoid this special case and
finish the fault in that case as well inside the DAX fault handler. It
will allow us for easier iomap handling.

Reviewed-by: Ross Zwisler 
Signed-off-by: Jan Kara 
Signed-off-by: Dan Williams

dax: Avoid page invalidation races and unnecessary radix tree traversals

2016-12-27T04:29:24+00:00

Currently dax_iomap_rw() takes care of invalidating page tables and
evicting hole pages from the radix tree when write(2) to the file
happens. This invalidation is only necessary when there is some block
allocation resulting from write(2). Furthermore in current place the
invalidation is racy wrt page fault instantiating a hole page just after
we have invalidated it.

So perform the page invalidation inside dax_iomap_actor() where we can
do it only when really necessary and after blocks have been allocated so
nobody will be instantiating new hole pages anymore.

Reviewed-by: Christoph Hellwig 
Reviewed-by: Ross Zwisler 
Signed-off-by: Jan Kara 
Signed-off-by: Dan Williams

mm: Invalidate DAX radix tree entries only if appropriate

2016-12-27T04:29:24+00:00

Currently invalidate_inode_pages2_range() and invalidate_mapping_pages()
just delete all exceptional radix tree entries they find. For DAX this
is not desirable as we track cache dirtiness in these entries and when
they are evicted, we may not flush caches although it is necessary. This
can for example manifest when we write to the same block both via mmap
and via write(2) (to different offsets) and fsync(2) then does not
properly flush CPU caches when modification via write(2) was the last
one.

Create appropriate DAX functions to handle invalidation of DAX entries
for invalidate_inode_pages2_range() and invalidate_mapping_pages() and
wire them up into the corresponding mm functions.

Acked-by: Johannes Weiner 
Reviewed-by: Ross Zwisler 
Signed-off-by: Jan Kara 
Signed-off-by: Dan Williams

ext2: Return BH_New buffers for zeroed blocks

2016-12-27T04:29:24+00:00

So far we did not return BH_New buffers from ext2_get_blocks() when we
allocated and zeroed-out a block for DAX inode to avoid racy zeroing in
DAX code. This zeroing is gone these days so we can remove the
workaround.

Reviewed-by: Ross Zwisler 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Jan Kara 
Signed-off-by: Dan Williams

ktime: Get rid of ktime_equal()

2016-12-25T16:21:23+00:00

No point in going through loops and hoops instead of just comparing the
values.

Signed-off-by: Thomas Gleixner 
Cc: Peter Zijlstra

ktime: Cleanup ktime_set() usage

2016-12-25T16:21:22+00:00

ktime_set(S,N) was required for the timespec storage type and is still
useful for situations where a Seconds and Nanoseconds part of a time value
needs to be converted. For anything where the Seconds argument is 0, this
is pointless and can be replaced with a simple assignment.

Signed-off-by: Thomas Gleixner 
Cc: Peter Zijlstra

ktime: Get rid of the union

2016-12-25T16:21:22+00:00

ktime is a union because the initial implementation stored the time in
scalar nanoseconds on 64 bit machine and in a endianess optimized timespec
variant for 32bit machines. The Y2038 cleanup removed the timespec variant
and switched everything to scalar nanoseconds. The union remained, but
become completely pointless.

Get rid of the union and just keep ktime_t as simple typedef of type s64.

The conversion was done with coccinelle and some manual mopping up.

Signed-off-by: Thomas Gleixner 
Cc: Peter Zijlstra

Replace with globally

2016-12-24T19:46:01+00:00

This was entirely automated, using the script by Al:

  PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*'
  sed -i -e "s!$PATT!#include !" \
        $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)

to do the replacement at the end of the merge window.

Requested-by: Al Viro 
Signed-off-by: Linus Torvalds