The patch titled
readahead: remove the local copy of ra in do_generic_mapping_read()
has been added to the -mm tree. Its filename is
readahead-remove-the-local-copy-of-ra-in-do_generic_mapping_read.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: readahead: remove the local copy of ra in do_generic_mapping_read()
From: Fengguang Wu <wfg@xxxxxxxxxxxxxxxx>
The local copy of ra in do_generic_mapping_read() can now go away.
It predates readanead(req_size). In a time when the readahead code was called
on *every* single page. Hence a local has to be made to reduce the chance of
the readahead state being overwritten by a concurrent reader. More details
in: Linux: Random File I/O Regressions In 2.6
<http://kerneltrap.org/node/3039>
Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx>
Signed-off-by: Fengguang Wu <wfg@xxxxxxxxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/filemap.c | 20 +++++++++-----------
1 file changed, 9 insertions(+), 11 deletions(-)
diff -puN mm/filemap.c~readahead-remove-the-local-copy-of-ra-in-do_generic_mapping_read mm/filemap.c
--- a/mm/filemap.c~readahead-remove-the-local-copy-of-ra-in-do_generic_mapping_read
+++ a/mm/filemap.c
@@ -859,7 +859,7 @@ static void shrink_readahead_size_eio(st
* It may be NULL.
*/
void do_generic_mapping_read(struct address_space *mapping,
- struct file_ra_state *_ra,
+ struct file_ra_state *ra,
struct file *filp,
loff_t *ppos,
read_descriptor_t *desc,
@@ -874,13 +874,12 @@ void do_generic_mapping_read(struct addr
unsigned int prev_offset;
struct page *cached_page;
int error;
- struct file_ra_state ra = *_ra;
cached_page = NULL;
index = *ppos >> PAGE_CACHE_SHIFT;
next_index = index;
- prev_index = ra.prev_pos >> PAGE_CACHE_SHIFT;
- prev_offset = ra.prev_pos & (PAGE_CACHE_SIZE-1);
+ prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT;
+ prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1);
last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
offset = *ppos & ~PAGE_CACHE_MASK;
@@ -895,7 +894,7 @@ find_page:
page = find_get_page(mapping, index);
if (!page) {
page_cache_sync_readahead(mapping,
- &ra, filp,
+ ra, filp,
index, last_index - index);
page = find_get_page(mapping, index);
if (unlikely(page == NULL))
@@ -903,7 +902,7 @@ find_page:
}
if (PageReadahead(page)) {
page_cache_async_readahead(mapping,
- &ra, filp, page,
+ ra, filp, page,
index, last_index - index);
}
if (!PageUptodate(page))
@@ -1014,7 +1013,7 @@ readpage:
}
unlock_page(page);
error = -EIO;
- shrink_readahead_size_eio(filp, &ra);
+ shrink_readahead_size_eio(filp, ra);
goto readpage_error;
}
unlock_page(page);
@@ -1054,10 +1053,9 @@ no_cached_page:
}
out:
- *_ra = ra;
- _ra->prev_pos = prev_index;
- _ra->prev_pos <<= PAGE_CACHE_SHIFT;
- _ra->prev_pos |= prev_offset;
+ ra->prev_pos = prev_index;
+ ra->prev_pos <<= PAGE_CACHE_SHIFT;
+ ra->prev_pos |= prev_offset;
*ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
if (cached_page)
_
Patches currently in -mm which might be from wfg@xxxxxxxxxxxxxxxx are
readahead-compacting-file_ra_state.patch
readahead-mmap-read-around-simplification.patch
readahead-combine-file_ra_stateprev_index-prev_offset-into-prev_pos.patch
readahead-combine-file_ra_stateprev_index-prev_offset-into-prev_pos-fix.patch
radixtree-introduce-radix_tree_scan_hole.patch
readahead-basic-support-of-interleaved-reads.patch
readahead-remove-the-local-copy-of-ra-in-do_generic_mapping_read.patch
readahead-remove-several-readahead-macros.patch
readahead-remove-the-limit-max_sectors_kb-imposed-on-max_readahead_kb.patch
filemap-trivial-code-cleanups.patch
filemap-convert-some-unsigned-long-to-pgoff_t.patch
convert-ill-defined-log2-to-ilog2.patch
-
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