Commit da309e8c authored by Amir Goldstein's avatar Amir Goldstein Committed by Miklos Szeredi
Browse files

ovl: factor out ovl_map_dev_ino() helper 



A helper for ovl_getattr() to map the values of st_dev and st_ino
according to constant st_ino rules.

Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 8f35cf51

fs/overlayfs/inode.c

+49 −39
Original line number Diff line number Diff line
@@ -16,13 +16,6 @@ 
#include "overlayfs.h"





static dev_t ovl_get_pseudo_dev(struct dentry *dentry)

{

	struct ovl_entry *oe = dentry->d_fsdata;



	return oe->lowerstack[0].layer->pseudo_dev;

}



int ovl_setattr(struct dentry *dentry, struct iattr *attr)

{

	int err;
@@ -66,6 +59,43 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr) 
	return err;

}



static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat,

			   struct ovl_layer *lower_layer)

{

	bool samefs = ovl_same_sb(dentry->d_sb);



	if (samefs) {

		/*

		 * When all layers are on the same fs, all real inode

		 * number are unique, so we use the overlay st_dev,

		 * which is friendly to du -x.

		 */

		stat->dev = dentry->d_sb->s_dev;

	} else if (S_ISDIR(dentry->d_inode->i_mode)) {

		/*

		 * Always use the overlay st_dev for directories, so 'find

		 * -xdev' will scan the entire overlay mount and won't cross the

		 * overlay mount boundaries.

		 *

		 * If not all layers are on the same fs the pair {real st_ino;

		 * overlay st_dev} is not unique, so use the non persistent

		 * overlay st_ino for directories.

		 */

		stat->dev = dentry->d_sb->s_dev;

		stat->ino = dentry->d_inode->i_ino;

	} else if (lower_layer) {

		/*

		 * For non-samefs setup, if we cannot map all layers st_ino

		 * to a unified address space, we need to make sure that st_dev

		 * is unique per layer. Upper layer uses real st_dev and lower

		 * layers use the unique anonymous bdev.

		 */

		stat->dev = lower_layer->pseudo_dev;

	}



	return 0;

}



int ovl_getattr(const struct path *path, struct kstat *stat,

		u32 request_mask, unsigned int flags)

{
@@ -75,6 +105,7 @@ int ovl_getattr(const struct path *path, struct kstat *stat, 
	const struct cred *old_cred;

	bool is_dir = S_ISDIR(dentry->d_inode->i_mode);

	bool samefs = ovl_same_sb(dentry->d_sb);

	struct ovl_layer *lower_layer = NULL;

	int err;



	type = ovl_path_real(dentry, &realpath);
@@ -84,14 +115,16 @@ int ovl_getattr(const struct path *path, struct kstat *stat, 
		goto out;



	/*

	 * For non-dir or same fs, we use st_ino of the copy up origin, if we

	 * know it. This guaranties constant st_dev/st_ino across copy up.

	 * For non-dir or same fs, we use st_ino of the copy up origin.

	 * This guaranties constant st_dev/st_ino across copy up.

	 *

	 * If filesystem supports NFS export ops, this also guaranties

	 * If lower filesystem supports NFS file handles, this also guaranties

	 * persistent st_ino across mount cycle.

	 */

	if (!is_dir || samefs) {

		if (OVL_TYPE_ORIGIN(type)) {

		if (!OVL_TYPE_UPPER(type)) {

			lower_layer = ovl_layer_lower(dentry);

		} else if (OVL_TYPE_ORIGIN(type)) {

			struct kstat lowerstat;

			u32 lowermask = STATX_INO | (!is_dir ? STATX_NLINK : 0);
@@ -120,38 +153,15 @@ int ovl_getattr(const struct path *path, struct kstat *stat, 
			    (!ovl_verify_lower(dentry->d_sb) &&

			     (is_dir || lowerstat.nlink == 1))) {

				stat->ino = lowerstat.ino;

				stat->dev = ovl_get_pseudo_dev(dentry);

			}

				lower_layer = ovl_layer_lower(dentry);

			}

		if (samefs) {

			/*

			 * When all layers are on the same fs, all real inode

			 * number are unique, so we use the overlay st_dev,

			 * which is friendly to du -x.

			 */

			stat->dev = dentry->d_sb->s_dev;

		} else if (!OVL_TYPE_UPPER(type)) {

			/*

			 * For non-samefs setup, to make sure that st_dev/st_ino

			 * pair is unique across the system, we use a unique

			 * anonymous st_dev for lower layer inode.

			 */

			stat->dev = ovl_get_pseudo_dev(dentry);

		}

	} else {

		/*

		 * Always use the overlay st_dev for directories, so 'find

		 * -xdev' will scan the entire overlay mount and won't cross the

		 * overlay mount boundaries.

		 *

		 * If not all layers are on the same fs the pair {real st_ino;

		 * overlay st_dev} is not unique, so use the non persistent

		 * overlay st_ino for directories.

		 */

		stat->dev = dentry->d_sb->s_dev;

		stat->ino = dentry->d_inode->i_ino;

	}



	err = ovl_map_dev_ino(dentry, stat, lower_layer);

	if (err)

		goto out;



	/*

	 * It's probably not worth it to count subdirs to get the

	 * correct link count.  nlink=1 seems to pacify 'find' and

fs/overlayfs/overlayfs.h

+1 −0
Original line number Diff line number Diff line
@@ -215,6 +215,7 @@ void ovl_path_lower(struct dentry *dentry, struct path *path); 
enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);

struct dentry *ovl_dentry_upper(struct dentry *dentry);

struct dentry *ovl_dentry_lower(struct dentry *dentry);

struct ovl_layer *ovl_layer_lower(struct dentry *dentry);

struct dentry *ovl_dentry_real(struct dentry *dentry);

struct dentry *ovl_i_dentry_upper(struct inode *inode);

struct inode *ovl_inode_upper(struct inode *inode);

fs/overlayfs/util.c

+7 −0
Original line number Diff line number Diff line
@@ -172,6 +172,13 @@ struct dentry *ovl_dentry_lower(struct dentry *dentry) 
	return oe->numlower ? oe->lowerstack[0].dentry : NULL;

}



struct ovl_layer *ovl_layer_lower(struct dentry *dentry)

{

	struct ovl_entry *oe = dentry->d_fsdata;



	return oe->numlower ? oe->lowerstack[0].layer : NULL;

}



struct dentry *ovl_dentry_real(struct dentry *dentry)

{

	return ovl_dentry_upper(dentry) ?: ovl_dentry_lower(dentry);