Commit 41665644 authored by Amir Goldstein's avatar Amir Goldstein
Browse files

ovl: prepare for lazy lookup of lowerdata inode 



Make the code handle the case of numlower > 1 and missing lowerdata
dentry gracefully.

Missing lowerdata dentry is an indication for lazy lookup of lowerdata
and in that case the lowerdata_redirect path is stored in ovl_inode.

Following commits will defer lookup and perform the lazy lookup on
access.

Reviewed-by: default avatarAlexander Larsson <alexl@redhat.com>
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 2b21da92

fs/overlayfs/file.c

+7 −0
Original line number Diff line number Diff line
@@ -115,6 +115,9 @@ static int ovl_real_fdget_meta(const struct file *file, struct fd *real, 
		ovl_path_real(dentry, &realpath);

	else

		ovl_path_realdata(dentry, &realpath);

	/* TODO: lazy lookup of lowerdata */

	if (!realpath.dentry)

		return -EIO;



	/* Has it been copied up since we'd opened it? */

	if (unlikely(file_inode(real->file) != d_inode(realpath.dentry))) {
@@ -158,6 +161,10 @@ static int ovl_open(struct inode *inode, struct file *file) 
	file->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);



	ovl_path_realdata(dentry, &realpath);

	/* TODO: lazy lookup of lowerdata */

	if (!realpath.dentry)

		return -EIO;



	realfile = ovl_open_realfile(file, &realpath);

	if (IS_ERR(realfile))

		return PTR_ERR(realfile);

fs/overlayfs/inode.c

+14 −4
Original line number Diff line number Diff line
@@ -240,15 +240,22 @@ int ovl_getattr(struct mnt_idmap *idmap, const struct path *path, 
			/*

			 * If lower is not same as lowerdata or if there was

			 * no origin on upper, we can end up here.

			 * With lazy lowerdata lookup, guess lowerdata blocks

			 * from size to avoid lowerdata lookup on stat(2).

			 */

			struct kstat lowerdatastat;

			u32 lowermask = STATX_BLOCKS;



			ovl_path_lowerdata(dentry, &realpath);

			if (realpath.dentry) {

				err = vfs_getattr(&realpath, &lowerdatastat,

						  lowermask, flags);

				if (err)

					goto out;

			} else {

				lowerdatastat.blocks =

					round_up(stat->size, stat->blksize) >> 9;

			}

			stat->blocks = lowerdatastat.blocks;

		}

	}
@@ -709,6 +716,9 @@ static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, 
	struct inode *realinode = ovl_inode_realdata(inode);

	const struct cred *old_cred;



	if (!realinode)

		return -EIO;



	if (!realinode->i_op->fiemap)

		return -EOPNOTSUPP;

fs/overlayfs/super.c

+11 −0
Original line number Diff line number Diff line
@@ -81,6 +81,14 @@ static struct dentry *ovl_d_real(struct dentry *dentry, 
	if (real && !inode && ovl_has_upperdata(d_inode(dentry)))

		return real;



	/*

	 * XXX: We may need lazy lookup of lowerdata for !inode case to return

	 * the real lowerdata dentry.  The only current caller of d_real() with

	 * NULL inode is d_real_inode() from trace_uprobe and this caller is

	 * likely going to be followed reading from the file, before placing

	 * uprobes on offset within the file, so lowerdata should be available

	 * when setting the uprobe.

	 */

	lower = ovl_dentry_lowerdata(dentry);

	if (!lower)

		goto bug;
@@ -103,6 +111,9 @@ static int ovl_revalidate_real(struct dentry *d, unsigned int flags, bool weak) 
{

	int ret = 1;



	if (!d)

		return 1;



	if (weak) {

		if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE)

			ret =  d->d_op->d_weak_revalidate(d, flags);

fs/overlayfs/util.c

+1 −1
Original line number Diff line number Diff line
@@ -159,7 +159,7 @@ void ovl_dentry_init_flags(struct dentry *dentry, struct dentry *upperdentry, 


	if (upperdentry)

		flags |= upperdentry->d_flags;

	for (i = 0; i < ovl_numlower(oe); i++)

	for (i = 0; i < ovl_numlower(oe) && lowerstack[i].dentry; i++)

		flags |= lowerstack[i].dentry->d_flags;



	spin_lock(&dentry->d_lock);