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Date: Thu, 31 Jan 2013 22:49:50 +0100
From: Jan Kara <jack@...e.cz>
To: LKML <linux-kernel@...r.kernel.org>
Cc: linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
Jan Kara <jack@...e.cz>
Subject: [PATCH 2/6] fs: Take mapping lock in generic read paths
Add mapping lock to struct address_space and grab it in all paths
creating pages in page cache to read data into them. That means buffered
read, readahead, and page fault code.
Signed-off-by: Jan Kara <jack@...e.cz>
---
fs/inode.c | 2 ++
include/linux/fs.h | 4 ++++
include/linux/pagemap.h | 2 ++
mm/filemap.c | 21 ++++++++++++++++++---
mm/readahead.c | 8 ++++----
5 files changed, 30 insertions(+), 7 deletions(-)
diff --git a/fs/inode.c b/fs/inode.c
index 14084b7..85db16c 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -168,6 +168,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
mapping->private_data = NULL;
mapping->backing_dev_info = &default_backing_dev_info;
mapping->writeback_index = 0;
+ range_lock_tree_init(&mapping->mapping_lock);
/*
* If the block_device provides a backing_dev_info for client
@@ -513,6 +514,7 @@ void clear_inode(struct inode *inode)
BUG_ON(!list_empty(&inode->i_data.private_list));
BUG_ON(!(inode->i_state & I_FREEING));
BUG_ON(inode->i_state & I_CLEAR);
+ BUG_ON(inode->i_data.mapping_lock.root.rb_node);
/* don't need i_lock here, no concurrent mods to i_state */
inode->i_state = I_FREEING | I_CLEAR;
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 7617ee0..2027d25 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -27,6 +27,7 @@
#include <linux/lockdep.h>
#include <linux/percpu-rwsem.h>
#include <linux/blk_types.h>
+#include <linux/range_lock.h>
#include <asm/byteorder.h>
#include <uapi/linux/fs.h>
@@ -420,6 +421,9 @@ struct address_space {
spinlock_t private_lock; /* for use by the address_space */
struct list_head private_list; /* ditto */
void *private_data; /* ditto */
+ struct range_lock_tree mapping_lock; /* Lock protecting creation /
+ * eviction of pages from
+ * the mapping */
} __attribute__((aligned(sizeof(long))));
/*
* On most architectures that alignment is already the case; but
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 6da609d..ba81ea9 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -537,6 +537,8 @@ int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
pgoff_t index, gfp_t gfp_mask);
int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
pgoff_t index, gfp_t gfp_mask);
+int add_to_page_cache_read(struct page *page, struct address_space *mapping,
+ pgoff_t offset, gfp_t gfp_mask);
extern void delete_from_page_cache(struct page *page);
extern void __delete_from_page_cache(struct page *page);
int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask);
diff --git a/mm/filemap.c b/mm/filemap.c
index 83efee7..4826cb4 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -491,6 +491,20 @@ int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
}
EXPORT_SYMBOL_GPL(add_to_page_cache_lru);
+int add_to_page_cache_read(struct page *page, struct address_space *mapping,
+ pgoff_t offset, gfp_t gfp_mask)
+{
+ struct range_lock mapping_lock;
+ int ret;
+
+ range_lock_init(&mapping_lock, offset, offset);
+ range_lock(&mapping->mapping_lock, &mapping_lock);
+ ret = add_to_page_cache_lru(page, mapping, offset, gfp_mask);
+ range_unlock(&mapping->mapping_lock, &mapping_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(add_to_page_cache_read);
+
#ifdef CONFIG_NUMA
struct page *__page_cache_alloc(gfp_t gfp)
{
@@ -1274,7 +1288,7 @@ no_cached_page:
desc->error = -ENOMEM;
goto out;
}
- error = add_to_page_cache_lru(page, mapping,
+ error = add_to_page_cache_read(page, mapping,
index, GFP_KERNEL);
if (error) {
page_cache_release(page);
@@ -1493,7 +1507,8 @@ static int page_cache_read(struct file *file, pgoff_t offset)
if (!page)
return -ENOMEM;
- ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
+ ret = add_to_page_cache_read(page, mapping, offset,
+ GFP_KERNEL);
if (ret == 0)
ret = mapping->a_ops->readpage(file, page);
else if (ret == -EEXIST)
@@ -1790,7 +1805,7 @@ repeat:
page = __page_cache_alloc(gfp | __GFP_COLD);
if (!page)
return ERR_PTR(-ENOMEM);
- err = add_to_page_cache_lru(page, mapping, index, gfp);
+ err = add_to_page_cache_read(page, mapping, index, gfp);
if (unlikely(err)) {
page_cache_release(page);
if (err == -EEXIST)
diff --git a/mm/readahead.c b/mm/readahead.c
index 7963f23..28a5e40 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -89,7 +89,7 @@ int read_cache_pages(struct address_space *mapping, struct list_head *pages,
while (!list_empty(pages)) {
page = list_to_page(pages);
list_del(&page->lru);
- if (add_to_page_cache_lru(page, mapping,
+ if (add_to_page_cache_read(page, mapping,
page->index, GFP_KERNEL)) {
read_cache_pages_invalidate_page(mapping, page);
continue;
@@ -126,11 +126,11 @@ static int read_pages(struct address_space *mapping, struct file *filp,
for (page_idx = 0; page_idx < nr_pages; page_idx++) {
struct page *page = list_to_page(pages);
+
list_del(&page->lru);
- if (!add_to_page_cache_lru(page, mapping,
- page->index, GFP_KERNEL)) {
+ if (!add_to_page_cache_read(page, mapping,
+ page->index, GFP_KERNEL))
mapping->a_ops->readpage(filp, page);
- }
page_cache_release(page);
}
ret = 0;
--
1.7.1
--
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