Commit c21c839b authored by Chengguang Xu's avatar Chengguang Xu Committed by Miklos Szeredi
Browse files

ovl: whiteout inode sharing 



Share inode with different whiteout files for saving inode and speeding up
delete operation.

If EMLINK is encountered when linking a shared whiteout, create a new one.
In case of any other error, disable sharing for this super block.

Note: ofs->whiteout is protected by inode lock on workdir.

Signed-off-by: default avatarChengguang Xu <cgxu519@mykernel.net>
Reviewed-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 654255fa

fs/overlayfs/dir.c

+37 −12
Original line number Diff line number Diff line
@@ -62,35 +62,59 @@ struct dentry *ovl_lookup_temp(struct dentry *workdir) 
}



/* caller holds i_mutex on workdir */

static struct dentry *ovl_whiteout(struct dentry *workdir)

static struct dentry *ovl_whiteout(struct ovl_fs *ofs)

{

	int err;

	struct dentry *whiteout;

	struct dentry *workdir = ofs->workdir;

	struct inode *wdir = workdir->d_inode;



	if (!ofs->whiteout) {

		whiteout = ovl_lookup_temp(workdir);

		if (IS_ERR(whiteout))

		return whiteout;

			goto out;



		err = ovl_do_whiteout(wdir, whiteout);

		if (err) {

			dput(whiteout);

			whiteout = ERR_PTR(err);

			goto out;

		}

		ofs->whiteout = whiteout;

	}



	if (ofs->share_whiteout) {

		whiteout = ovl_lookup_temp(workdir);

		if (IS_ERR(whiteout))

			goto out;



		err = ovl_do_link(ofs->whiteout, wdir, whiteout);

		if (!err)

			goto out;



		if (err != -EMLINK) {

			pr_warn("Failed to link whiteout - disabling whiteout inode sharing(nlink=%u, err=%i)\n",

				ofs->whiteout->d_inode->i_nlink, err);

			ofs->share_whiteout = false;

		}

		dput(whiteout);

	}

	whiteout = ofs->whiteout;

	ofs->whiteout = NULL;

out:

	return whiteout;

}



/* Caller must hold i_mutex on both workdir and dir */

int ovl_cleanup_and_whiteout(struct dentry *workdir, struct inode *dir,

int ovl_cleanup_and_whiteout(struct ovl_fs *ofs, struct inode *dir,

			     struct dentry *dentry)

{

	struct inode *wdir = workdir->d_inode;

	struct inode *wdir = ofs->workdir->d_inode;

	struct dentry *whiteout;

	int err;

	int flags = 0;



	whiteout = ovl_whiteout(workdir);

	whiteout = ovl_whiteout(ofs);

	err = PTR_ERR(whiteout);

	if (IS_ERR(whiteout))

		return err;
@@ -715,6 +739,7 @@ static bool ovl_matches_upper(struct dentry *dentry, struct dentry *upper) 
static int ovl_remove_and_whiteout(struct dentry *dentry,

				   struct list_head *list)

{

	struct ovl_fs *ofs = OVL_FS(dentry->d_sb);

	struct dentry *workdir = ovl_workdir(dentry);

	struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);

	struct dentry *upper;
@@ -748,7 +773,7 @@ static int ovl_remove_and_whiteout(struct dentry *dentry, 
		goto out_dput_upper;

	}



	err = ovl_cleanup_and_whiteout(workdir, d_inode(upperdir), upper);

	err = ovl_cleanup_and_whiteout(ofs, d_inode(upperdir), upper);

	if (err)

		goto out_d_drop;

fs/overlayfs/overlayfs.h

+1 −1
Original line number Diff line number Diff line
@@ -455,7 +455,7 @@ static inline void ovl_copyflags(struct inode *from, struct inode *to) 


/* dir.c */

extern const struct inode_operations ovl_dir_inode_operations;

int ovl_cleanup_and_whiteout(struct dentry *workdir, struct inode *dir,

int ovl_cleanup_and_whiteout(struct ovl_fs *ofs, struct inode *dir,

			     struct dentry *dentry);

struct ovl_cattr {

	dev_t rdev;

fs/overlayfs/ovl_entry.h

+3 −0
Original line number Diff line number Diff line
@@ -68,6 +68,7 @@ struct ovl_fs { 
	/* Did we take the inuse lock? */

	bool upperdir_locked;

	bool workdir_locked;

	bool share_whiteout;

	/* Traps in ovl inode cache */

	struct inode *upperdir_trap;

	struct inode *workbasedir_trap;
@@ -77,6 +78,8 @@ struct ovl_fs { 
	int xino_mode;

	/* For allocation of non-persistent inode numbers */

	atomic_long_t last_ino;

	/* Whiteout dentry cache */

	struct dentry *whiteout;

};



static inline struct ovl_fs *OVL_FS(struct super_block *sb)

fs/overlayfs/readdir.c

+1 −1
Original line number Diff line number Diff line
@@ -1154,7 +1154,7 @@ int ovl_indexdir_cleanup(struct ovl_fs *ofs) 
			 * Whiteout orphan index to block future open by

			 * handle after overlay nlink dropped to zero.

			 */

			err = ovl_cleanup_and_whiteout(indexdir, dir, index);

			err = ovl_cleanup_and_whiteout(ofs, dir, index);

		} else {

			/* Cleanup orphan index entries */

			err = ovl_cleanup(dir, index);

fs/overlayfs/super.c

+4 −0
Original line number Diff line number Diff line
@@ -217,6 +217,7 @@ static void ovl_free_fs(struct ovl_fs *ofs) 
	iput(ofs->indexdir_trap);

	iput(ofs->workdir_trap);

	iput(ofs->upperdir_trap);

	dput(ofs->whiteout);

	dput(ofs->indexdir);

	dput(ofs->workdir);

	if (ofs->workdir_locked)
@@ -1776,6 +1777,9 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) 
	if (!cred)

		goto out_err;



	/* Is there a reason anyone would want not to share whiteouts? */

	ofs->share_whiteout = true;



	ofs->config.index = ovl_index_def;

	ofs->config.nfs_export = ovl_nfs_export_def;

	ofs->config.xino = ovl_xino_def();

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