Commit 2002df85 authored by Vivek Goyal's avatar Vivek Goyal Committed by Miklos Szeredi
Browse files

ovl: Add helper ovl_already_copied_up() 



There are couple of places where we need to know if file is already copied
up (in lockless manner).  Right now its open coded and there are only two
conditions to check.  Soon this patch series will introduce another
condition to check and Amir wants to introduce one more.  So introduce a
helper instead to check this so that code is easier to read.

Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Reviewed-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 44d5bf10

fs/overlayfs/copy_up.c

+2 −18
Original line number Diff line number Diff line
@@ -761,21 +761,7 @@ int ovl_copy_up_flags(struct dentry *dentry, int flags) 
		struct dentry *next;

		struct dentry *parent = NULL;



		/*

		 * Check if copy-up has happened as well as for upper alias (in

		 * case of hard links) is there.

		 *

		 * Both checks are lockless:

		 *  - false negatives: will recheck under oi->lock

		 *  - false positives:

		 *    + ovl_dentry_upper() uses memory barriers to ensure the

		 *      upper dentry is up-to-date

		 *    + ovl_dentry_has_upper_alias() relies on locking of

		 *      upper parent i_rwsem to prevent reordering copy-up

		 *      with rename.

		 */

		if (ovl_dentry_upper(dentry) &&

		    (ovl_dentry_has_upper_alias(dentry) || disconnected))

		if (ovl_already_copied_up(dentry))

			break;



		next = dget(dentry);
@@ -803,9 +789,7 @@ int ovl_copy_up_flags(struct dentry *dentry, int flags) 
static bool ovl_open_need_copy_up(struct dentry *dentry, int flags)

{

	/* Copy up of disconnected dentry does not set upper alias */

	if (ovl_dentry_upper(dentry) &&

	    (ovl_dentry_has_upper_alias(dentry) ||

	     (dentry->d_flags & DCACHE_DISCONNECTED)))

	if (ovl_already_copied_up(dentry))

		return false;



	if (special_file(d_inode(dentry)->i_mode))

fs/overlayfs/overlayfs.h

+1 −0
Original line number Diff line number Diff line
@@ -238,6 +238,7 @@ bool ovl_is_whiteout(struct dentry *dentry); 
struct file *ovl_path_open(struct path *path, int flags);

int ovl_copy_up_start(struct dentry *dentry);

void ovl_copy_up_end(struct dentry *dentry);

bool ovl_already_copied_up(struct dentry *dentry);

bool ovl_check_origin_xattr(struct dentry *dentry);

bool ovl_check_dir_xattr(struct dentry *dentry, const char *name);

int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,

fs/overlayfs/util.c

+25 −1
Original line number Diff line number Diff line
@@ -377,13 +377,37 @@ struct file *ovl_path_open(struct path *path, int flags) 
	return dentry_open(path, flags | O_NOATIME, current_cred());

}



bool ovl_already_copied_up(struct dentry *dentry)

{

	bool disconnected = dentry->d_flags & DCACHE_DISCONNECTED;



	/*

	 * Check if copy-up has happened as well as for upper alias (in

	 * case of hard links) is there.

	 *

	 * Both checks are lockless:

	 *  - false negatives: will recheck under oi->lock

	 *  - false positives:

	 *    + ovl_dentry_upper() uses memory barriers to ensure the

	 *      upper dentry is up-to-date

	 *    + ovl_dentry_has_upper_alias() relies on locking of

	 *      upper parent i_rwsem to prevent reordering copy-up

	 *      with rename.

	 */

	if (ovl_dentry_upper(dentry) &&

	    (ovl_dentry_has_upper_alias(dentry) || disconnected))

		return true;



	return false;

}



int ovl_copy_up_start(struct dentry *dentry)

{

	struct ovl_inode *oi = OVL_I(d_inode(dentry));

	int err;



	err = mutex_lock_interruptible(&oi->lock);

	if (!err && ovl_dentry_has_upper_alias(dentry)) {

	if (!err && ovl_already_copied_up(dentry)) {

		err = 1; /* Already copied up */

		mutex_unlock(&oi->lock);

	}

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