Commit c39a7f84 authored by Toshiyuki Okajima's avatar Toshiyuki Okajima Committed by Theodore Ts'o
Browse files

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: default avatarToshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
Cc: linux-fsdevel@vger.kernel.org
parent 6b082b53

fs/ext4/super.c

+20 −0
Original line number Original line Diff line number Diff line
@@ -907,6 +907,25 @@ static struct dentry *ext4_fh_to_parent(struct super_block *sb, struct fid *fid, 
				    ext4_nfs_get_inode);

				    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

#ifdef CONFIG_QUOTA

#define QTYPE2NAME(t) ((t) == USRQUOTA ? "user" : "group")

#define QTYPE2NAME(t) ((t) == USRQUOTA ? "user" : "group")

#define QTYPE2MOPT(on, t) ((t) == USRQUOTA?((on)##USRJQUOTA):((on)##GRPJQUOTA))

#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_read	= ext4_quota_read,

	.quota_write	= ext4_quota_write,

	.quota_write	= ext4_quota_write,

#endif

#endif

	.bdev_try_to_free_page = bdev_try_to_free_page,

};

};





static const struct export_operations ext4_export_ops = {

static const struct export_operations ext4_export_ops = {

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