[PATCH 3/3] ext4: provide function to release metadata pages under memory pressure
From: Theodore Ts'o <tytso@mit.edu>
Date: 2009-01-03 15:09:18
Also in:
linux-fsdevel
Subsystem:
ext4 file system, filesystems (vfs and infrastructure), the rest · Maintainers:
"Theodore Ts'o", Alexander Viro, Christian Brauner, Linus Torvalds
From: Toshiyuki Okajima <redacted> 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 <redacted> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: linux-fsdevel@vger.kernel.org --- fs/ext4/super.c | 19 +++++++++++++++++++ 1 files changed, 19 insertions(+), 0 deletions(-)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 0e0653d..980391d 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c@@ -907,6 +907,24 @@ 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); + 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 +989,7 @@ 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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1.6.0.4.8.g36f27.dirty