[PATCH 3/3] ext4: release block-device-mapping buffer_heads which have the filesystem
private data for avoiding oom-killer
Implement releasepage() of a client of a block device to release its private
data (journal_heads) and the page. The client is an ext4 filesystem.
This function is called from releasepage() of the block-device mapping,
blkdev_releasepage().
Signed-off-by: Toshiyuki Okajima <toshi.okajima@xxxxxxxxxxxxxx>
---
fs/ext4/ext4.h | 2 ++
fs/ext4/inode.c | 22 ++++++++++++++++++++++
fs/ext4/super.c | 4 ++++
3 files changed, 28 insertions(+)
diff -Nurp linux-2.6.28-rc4.orig/fs/ext4/ext4.h linux-2.6.28-rc4/fs/ext4/ext4.h
--- linux-2.6.28-rc4.orig/fs/ext4/ext4.h 2008-11-10 09:36:15.000000000 +0900
+++ linux-2.6.28-rc4/fs/ext4/ext4.h 2008-11-12 10:44:25.000000000 +0900
@@ -1095,6 +1095,8 @@ extern int ext4_chunk_trans_blocks(struc
extern int ext4_block_truncate_page(handle_t *handle,
struct address_space *mapping, loff_t from);
extern int ext4_page_mkwrite(struct vm_area_struct *vma, struct page *page);
+extern int ext4_release_metadata(void *client, struct page *page,
+ gfp_t wait);
/* ioctl.c */
extern long ext4_ioctl(struct file *, unsigned int, unsigned long);
diff -Nurp linux-2.6.28-rc4.orig/fs/ext4/inode.c linux-2.6.28-rc4/fs/ext4/inode.c
--- linux-2.6.28-rc4.orig/fs/ext4/inode.c 2008-11-10 09:36:15.000000000 +0900
+++ linux-2.6.28-rc4/fs/ext4/inode.c 2008-11-12 10:42:55.000000000 +0900
@@ -3002,6 +3002,28 @@ static int ext4_releasepage(struct page
}
/*
+ * ext4_release_metadata: try to release own page.
+ * The mapping of this page is block device's. Therefore try_to_free_buffers()
+ * cannot release it. As a result, a function which releases own page is
+ * required.
+ */
+int ext4_release_metadata(void *client, struct page *page, gfp_t wait)
+{
+ struct super_block *sb = (struct super_block*)client;
+ journal_t *journal;
+
+ WARN_ON(PageChecked(page));
+ if (!page_has_buffers(page))
+ return 0;
+ BUG_ON(EXT4_SB(sb) == NULL);
+ journal = EXT4_SB(sb)->s_journal;
+ if (journal != NULL)
+ return jbd2_journal_try_to_free_buffers(journal, page, wait);
+ else
+ return try_to_free_buffers(page);
+}
+
+/*
* If the O_DIRECT write will extend the file then add this inode to the
* orphan list. So recovery will truncate it back to the original size
* if the machine crashes during the write.
diff -Nurp linux-2.6.28-rc4.orig/fs/ext4/super.c linux-2.6.28-rc4/fs/ext4/super.c
--- linux-2.6.28-rc4.orig/fs/ext4/super.c 2008-11-10 09:36:15.000000000 +0900
+++ linux-2.6.28-rc4/fs/ext4/super.c 2008-11-12 12:04:58.000000000 +0900
@@ -3543,6 +3543,8 @@ static struct file_system_type ext4_fs_t
.name = "ext4",
.get_sb = ext4_get_sb,
.kill_sb = kill_block_super,
+ .release_metadata
+ = ext4_release_metadata,
.fs_flags = FS_REQUIRES_DEV,
};
@@ -3562,6 +3564,8 @@ static struct file_system_type ext4dev_f
.name = "ext4dev",
.get_sb = ext4dev_get_sb,
.kill_sb = kill_block_super,
+ .release_metadata
+ = ext4_release_metadata,
.fs_flags = FS_REQUIRES_DEV,
};
MODULE_ALIAS("ext4dev");
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