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authorToshiyuki Okajima <toshi.okajima@jp.fujitsu.com>2009-01-05 22:38:48 -0500
committerTheodore Ts'o <tytso@mit.edu>2009-01-05 22:38:48 -0500
commitc39a7f84d7845aa95d1c7c168f38215aedcc13c2 (patch)
tree3e9d741df74eef7e6438dfd9a7ab5a32dd5a5501
parent6b082b531228c43d454c082fc0f969da1695b060 (diff)
downloadop-kernel-dev-c39a7f84d7845aa95d1c7c168f38215aedcc13c2.zip
op-kernel-dev-c39a7f84d7845aa95d1c7c168f38215aedcc13c2.tar.gz
ext4: provide function to release metadata pages under memory pressure
Pages in the page cache belonging to ext4 data files are released via the ext4_releasepage() function specified in the ext4 inode's address_space_ops. However, metadata blocks (such as indirect blocks, directory blocks, etc) are managed via the block device address_space_ops, and they can not be released by try_to_free_buffers() if they have a journal head attached to them. To address this, we supply a release_metadata function which calls jbd2_journal_try_to_free_buffers() function to free the metadata, and which is called by the block device's blkdev_releasepage() function. Signed-off-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: linux-fsdevel@vger.kernel.org
-rw-r--r--fs/ext4/super.c20
1 files changed, 20 insertions, 0 deletions
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index a3321bf..e5ab520 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -907,6 +907,25 @@ static struct dentry *ext4_fh_to_parent(struct super_block *sb, struct fid *fid,
ext4_nfs_get_inode);
}
+/*
+ * Try to release metadata pages (indirect blocks, directories) which are
+ * mapped via the block device. Since these pages could have journal heads
+ * which would prevent try_to_free_buffers() from freeing them, we must use
+ * jbd2 layer's try_to_free_buffers() function to release them.
+ */
+static int bdev_try_to_free_page(struct super_block *sb, struct page *page, gfp_t wait)
+{
+ journal_t *journal = EXT4_SB(sb)->s_journal;
+
+ WARN_ON(PageChecked(page));
+ if (!page_has_buffers(page))
+ return 0;
+ if (journal)
+ return jbd2_journal_try_to_free_buffers(journal, page,
+ wait & ~__GFP_WAIT);
+ return try_to_free_buffers(page);
+}
+
#ifdef CONFIG_QUOTA
#define QTYPE2NAME(t) ((t) == USRQUOTA ? "user" : "group")
#define QTYPE2MOPT(on, t) ((t) == USRQUOTA?((on)##USRJQUOTA):((on)##GRPJQUOTA))
@@ -971,6 +990,7 @@ static const struct super_operations ext4_sops = {
.quota_read = ext4_quota_read,
.quota_write = ext4_quota_write,
#endif
+ .bdev_try_to_free_page = bdev_try_to_free_page,
};
static const struct export_operations ext4_export_ops = {
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