The patch titled
mm: restore KERNEL_DS optimisations
has been added to the -mm tree. Its filename is
mm-restore-kernel_ds-optimisations.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: mm: restore KERNEL_DS optimisations
From: Nick Piggin <npiggin@xxxxxxx>
Restore the KERNEL_DS optimisation, especially helpful to the 2copy write
path.
This may be a pretty questionable gain in most cases, especially after the
legacy 2copy write path is removed, but it doesn't cost much.
Signed-off-by: Nick Piggin <npiggin@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/filemap.c | 11 +++++++++--
1 files changed, 9 insertions(+), 2 deletions(-)
diff -puN mm/filemap.c~mm-restore-kernel_ds-optimisations mm/filemap.c
--- a/mm/filemap.c~mm-restore-kernel_ds-optimisations
+++ a/mm/filemap.c
@@ -2103,7 +2103,7 @@ static ssize_t generic_perform_write_2co
* cannot take a pagefault with the destination page locked.
* So pin the source page to copy it.
*/
- if (!PageUptodate(page)) {
+ if (!PageUptodate(page) && !segment_eq(get_fs(), KERNEL_DS)) {
unlock_page(page);
src_page = alloc_page(GFP_KERNEL);
@@ -2228,6 +2228,13 @@ static ssize_t generic_perform_write(str
const struct address_space_operations *a_ops = mapping->a_ops;
long status = 0;
ssize_t written = 0;
+ unsigned int flags = 0;
+
+ /*
+ * Copies from kernel address space cannot fail (NFSD is a big user).
+ */
+ if (segment_eq(get_fs(), KERNEL_DS))
+ flags |= AOP_FLAG_UNINTERRUPTIBLE;
do {
struct page *page;
@@ -2259,7 +2266,7 @@ again:
break;
}
- status = a_ops->write_begin(file, mapping, pos, bytes, 0,
+ status = a_ops->write_begin(file, mapping, pos, bytes, flags,
&page, &fsdata);
if (unlikely(status))
break;
_
Patches currently in -mm which might be from npiggin@xxxxxxx are
mm-fix-fault-vs-invalidate-race-for-linear-mappings.patch
mm-fix-fault-vs-invalidate-race-for-linear-mappings-fix.patch
mm-merge-populate-and-nopage-into-fault-fixes-nonlinear.patch
mm-merge-nopfn-into-fault.patch
mm-remove-legacy-cruft.patch
mm-debug-check-for-the-fault-vs-invalidate-race.patch
mm-fix-clear_page_dirty_for_io-vs-fault-race.patch
git-arm-master.patch
slob-rework-freelist-handling.patch
slob-remove-bigblock-tracking.patch
slob-improved-alignment-handling.patch
mm-revert-kernel_ds-buffered-write-optimisation.patch
revert-81b0c8713385ce1b1b9058e916edcf9561ad76d6.patch
revert-6527c2bdf1f833cc18e8f42bd97973d583e4aa83.patch
mm-clean-up-buffered-write-code.patch
mm-debug-write-deadlocks.patch
mm-trim-more-holes.patch
mm-buffered-write-cleanup.patch
mm-write-iovec-cleanup.patch
mm-fix-pagecache-write-deadlocks.patch
mm-buffered-write-iterator.patch
fs-fix-data-loss-on-error.patch
fs-introduce-write_begin-write_end-and-perform_write-aops.patch
mm-restore-kernel_ds-optimisations.patch
implement-simple-fs-aops.patch
block_dev-convert-to-new-aops.patch
ext2-convert-to-new-aops.patch
ext3-convert-to-new-aops.patch
ext4-convert-to-new-aops.patch
xfs-convert-to-new-aops.patch
fs-new-cont-helpers.patch
fat-convert-to-new-aops.patch
hfs-convert-to-new-aops.patch
hfsplus-convert-to-new-aops.patch
hpfs-convert-to-new-aops.patch
bfs-convert-to-new-aops.patch
qnx4-convert-to-new-aops.patch
reiserfs-use-generic-write.patch
reiserfs-convert-to-new-aops.patch
reiserfs-use-generic_cont_expand_simple.patch
with-reiserfs-no-longer-using-the-weird-generic_cont_expand-remove-it-completely.patch
nfs-convert-to-new-aops.patch
smb-convert-to-new-aops.patch
fuse-convert-to-new-aops.patch
hostfs-convert-to-new-aops.patch
jffs2-convert-to-new-aops.patch
ufs-convert-to-new-aops.patch
udf-convert-to-new-aops.patch
sysv-convert-to-new-aops.patch
minix-convert-to-new-aops.patch
jfs-convert-to-new-aops.patch
mm-document-fault_data-and-flags.patch
fs-introduce-some-page-buffer-invariants.patch
fs-introduce-write_begin-write_end-and-perform_write-aops-revoke.patch
-
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