ovl: allocate a container struct ovl_file for ovl private context

Instead of using ->private_data to point at realfile directly, so
that we can add more context per ovl open file.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>

diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 5cf529482a8a36538d5ffb5a6eb4523ec9f2d1b4..08e683917d121b1fe8f0f0b4d4ba4f0f3c72f47d 100644 (file)
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -1323,6 +1323,7 @@ static int ovl_create_tmpfile(struct file *file, struct dentry *dentry,
        const struct cred *old_cred, *new_cred = NULL;
        struct path realparentpath;
        struct file *realfile;
+       struct ovl_file *of;
        struct dentry *newdentry;
        /* It's okay to set O_NOATIME, since the owner will be current fsuid */
        int flags = file->f_flags | OVL_OPEN_FLAGS;
@@ -1344,14 +1345,21 @@ static int ovl_create_tmpfile(struct file *file, struct dentry *dentry,
        if (err)
                goto out_revert_creds;
 
+       of = ovl_file_alloc(realfile);
+       if (!of) {
+               fput(realfile);
+               err = -ENOMEM;
+               goto out_revert_creds;
+       }
+
        /* ovl_instantiate() consumes the newdentry reference on success */
        newdentry = dget(realfile->f_path.dentry);
        err = ovl_instantiate(dentry, inode, newdentry, false, file);
        if (!err) {
-               file->private_data = realfile;
+               file->private_data = of;
        } else {
                dput(newdentry);
-               fput(realfile);
+               ovl_file_free(of);
        }
 out_revert_creds:
        ovl_revert_creds(old_cred);
@@ -1407,7 +1415,7 @@ static int ovl_tmpfile(struct mnt_idmap *idmap, struct inode *dir,
 put_realfile:
        /* Without FMODE_OPENED ->release() won't be called on @file */
        if (!(file->f_mode & FMODE_OPENED))
-               fput(file->private_data);
+               ovl_file_free(file->private_data);
 put_inode:
        iput(inode);
 drop_write:

diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index 4a1cf45e3fa1407c83392e12387744b32766b0d7..0fa0795d335f75b1403b71b55746a68fd2fc24c5 100644 (file)
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -89,10 +89,32 @@ static int ovl_change_flags(struct file *file, unsigned int flags)
        return 0;
 }
 
+struct ovl_file {
+       struct file *realfile;
+};
+
+struct ovl_file *ovl_file_alloc(struct file *realfile)
+{
+       struct ovl_file *of = kzalloc(sizeof(struct ovl_file), GFP_KERNEL);
+
+       if (unlikely(!of))
+               return NULL;
+
+       of->realfile = realfile;
+       return of;
+}
+
+void ovl_file_free(struct ovl_file *of)
+{
+       fput(of->realfile);
+       kfree(of);
+}
+
 static int ovl_real_fdget_path(const struct file *file, struct fd *real,
                               struct path *realpath)
 {
-       struct file *realfile = file->private_data;
+       struct ovl_file *of = file->private_data;
+       struct file *realfile = of->realfile;
 
        real->word = (unsigned long)realfile;
 
@@ -144,6 +166,7 @@ static int ovl_open(struct inode *inode, struct file *file)
        struct dentry *dentry = file_dentry(file);
        struct file *realfile;
        struct path realpath;
+       struct ovl_file *of;
        int err;
 
        /* lazy lookup and verify lowerdata */
@@ -166,15 +189,20 @@ static int ovl_open(struct inode *inode, struct file *file)
        if (IS_ERR(realfile))
                return PTR_ERR(realfile);
 
-       file->private_data = realfile;
+       of = ovl_file_alloc(realfile);
+       if (!of) {
+               fput(realfile);
+               return -ENOMEM;
+       }
+
+       file->private_data = of;
 
        return 0;
 }
 
 static int ovl_release(struct inode *inode, struct file *file)
 {
-       fput(file->private_data);
-
+       ovl_file_free(file->private_data);
        return 0;
 }
 
@@ -426,13 +454,13 @@ static int ovl_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 
 static int ovl_mmap(struct file *file, struct vm_area_struct *vma)
 {
-       struct file *realfile = file->private_data;
+       struct ovl_file *of = file->private_data;
        struct backing_file_ctx ctx = {
                .cred = ovl_creds(file_inode(file)->i_sb),
                .accessed = ovl_file_accessed,
        };
 
-       return backing_file_mmap(realfile, vma, &ctx);
+       return backing_file_mmap(of->realfile, vma, &ctx);
 }
 
 static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len)

diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 7b7a6e3a43e2ba4fdffb7a559b00863feaa62abf..6e32eb9cd1b6e5429b9dbcdc3093dc7d39aa0995 100644 (file)
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -863,6 +863,9 @@ int ovl_real_fileattr_set(const struct path *realpath, struct fileattr *fa);
 int ovl_fileattr_get(struct dentry *dentry, struct fileattr *fa);
 int ovl_fileattr_set(struct mnt_idmap *idmap,
                     struct dentry *dentry, struct fileattr *fa);
+struct ovl_file;
+struct ovl_file *ovl_file_alloc(struct file *realfile);
+void ovl_file_free(struct ovl_file *of);
 
 /* copy_up.c */
 int ovl_copy_up(struct dentry *dentry);