[PATCH 23/71] cachefiles: get rid of PAGE_CACHE_* and page_cache_{get,release} macros

From: Kirill A. Shutemov
Date: Sun Mar 20 2016 - 14:58:02 EST


PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time ago
with promise that one day it will be possible to implement page cache with
bigger chunks than PAGE_SIZE.

This promise never materialized. And unlikely will.

We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE. And it's constant source of confusion on whether PAGE_CACHE_*
or PAGE_* constant should be used in a particular case, especially on the
border between fs and mm.

Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.

Let's stop pretending that pages in page cache are special. They are not.

The changes are pretty straight-forward:

- <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;

- PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};

- page_cache_get() -> get_page();

- page_cache_release() -> put_page();

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
---
fs/cachefiles/rdwr.c | 38 +++++++++++++++++++-------------------
1 file changed, 19 insertions(+), 19 deletions(-)

diff --git a/fs/cachefiles/rdwr.c b/fs/cachefiles/rdwr.c
index c0f3da3926a0..afbdc418966d 100644
--- a/fs/cachefiles/rdwr.c
+++ b/fs/cachefiles/rdwr.c
@@ -194,10 +194,10 @@ static void cachefiles_read_copier(struct fscache_operation *_op)
error = -EIO;
}

- page_cache_release(monitor->back_page);
+ put_page(monitor->back_page);

fscache_end_io(op, monitor->netfs_page, error);
- page_cache_release(monitor->netfs_page);
+ put_page(monitor->netfs_page);
fscache_retrieval_complete(op, 1);
fscache_put_retrieval(op);
kfree(monitor);
@@ -288,8 +288,8 @@ monitor_backing_page:
_debug("- monitor add");

/* install the monitor */
- page_cache_get(monitor->netfs_page);
- page_cache_get(backpage);
+ get_page(monitor->netfs_page);
+ get_page(backpage);
monitor->back_page = backpage;
monitor->monitor.private = backpage;
add_page_wait_queue(backpage, &monitor->monitor);
@@ -310,7 +310,7 @@ backing_page_already_present:
_debug("- present");

if (newpage) {
- page_cache_release(newpage);
+ put_page(newpage);
newpage = NULL;
}

@@ -342,7 +342,7 @@ success:

out:
if (backpage)
- page_cache_release(backpage);
+ put_page(backpage);
if (monitor) {
fscache_put_retrieval(monitor->op);
kfree(monitor);
@@ -363,7 +363,7 @@ io_error:
goto out;

nomem_page:
- page_cache_release(newpage);
+ put_page(newpage);
nomem_monitor:
fscache_put_retrieval(monitor->op);
kfree(monitor);
@@ -530,7 +530,7 @@ static int cachefiles_read_backing_file(struct cachefiles_object *object,
netpage->index, cachefiles_gfp);
if (ret < 0) {
if (ret == -EEXIST) {
- page_cache_release(netpage);
+ put_page(netpage);
fscache_retrieval_complete(op, 1);
continue;
}
@@ -538,10 +538,10 @@ static int cachefiles_read_backing_file(struct cachefiles_object *object,
}

/* install a monitor */
- page_cache_get(netpage);
+ get_page(netpage);
monitor->netfs_page = netpage;

- page_cache_get(backpage);
+ get_page(backpage);
monitor->back_page = backpage;
monitor->monitor.private = backpage;
add_page_wait_queue(backpage, &monitor->monitor);
@@ -555,10 +555,10 @@ static int cachefiles_read_backing_file(struct cachefiles_object *object,
unlock_page(backpage);
}

- page_cache_release(backpage);
+ put_page(backpage);
backpage = NULL;

- page_cache_release(netpage);
+ put_page(netpage);
netpage = NULL;
continue;

@@ -603,7 +603,7 @@ static int cachefiles_read_backing_file(struct cachefiles_object *object,
netpage->index, cachefiles_gfp);
if (ret < 0) {
if (ret == -EEXIST) {
- page_cache_release(netpage);
+ put_page(netpage);
fscache_retrieval_complete(op, 1);
continue;
}
@@ -612,14 +612,14 @@ static int cachefiles_read_backing_file(struct cachefiles_object *object,

copy_highpage(netpage, backpage);

- page_cache_release(backpage);
+ put_page(backpage);
backpage = NULL;

fscache_mark_page_cached(op, netpage);

/* the netpage is unlocked and marked up to date here */
fscache_end_io(op, netpage, 0);
- page_cache_release(netpage);
+ put_page(netpage);
netpage = NULL;
fscache_retrieval_complete(op, 1);
continue;
@@ -632,11 +632,11 @@ static int cachefiles_read_backing_file(struct cachefiles_object *object,
out:
/* tidy up */
if (newpage)
- page_cache_release(newpage);
+ put_page(newpage);
if (netpage)
- page_cache_release(netpage);
+ put_page(netpage);
if (backpage)
- page_cache_release(backpage);
+ put_page(backpage);
if (monitor) {
fscache_put_retrieval(op);
kfree(monitor);
@@ -644,7 +644,7 @@ out:

list_for_each_entry_safe(netpage, _n, list, lru) {
list_del(&netpage->lru);
- page_cache_release(netpage);
+ put_page(netpage);
fscache_retrieval_complete(op, 1);
}

--
2.7.0