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ANDROID: sdcardfs: use d_splice_alias

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adapted from wrapfs
commit 9671770ff8b9 ("Wrapfs: use d_splice_alias")

Refactor interpose code to allow lookup to use d_splice_alias.

Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
Signed-off-by: Daniel Rosenberg <drosen@google.com>
Bug: 35766959
Change-Id: Icf51db8658202c48456724275b03dc77f73f585b
This commit is contained in:
Daniel Rosenberg 2017-03-09 22:11:08 -08:00 committed by Amit Pundir
parent 63cd557652
commit 2e5e3fd117
1 changed files with 39 additions and 16 deletions
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55
fs/sdcardfs/lookup.c
View file

@ -164,27 +164,25 @@ struct inode *sdcardfs_iget(struct super_block *sb, struct inode *lower_inode, u
}
/*
* Connect a sdcardfs inode dentry/inode with several lower ones. This is
* the classic stackable file system "vnode interposition" action.
*
* @dentry: sdcardfs's dentry which interposes on lower one
* @sb: sdcardfs's super_block
* @lower_path: the lower path (caller does path_get/put)
* Helper interpose routine, called directly by ->lookup to handle
* spliced dentries.
*/
int sdcardfs_interpose(struct dentry *dentry, struct super_block *sb,
struct path *lower_path, userid_t id)
static struct dentry *__sdcardfs_interpose(struct dentry *dentry,
struct super_block *sb,
struct path *lower_path,
userid_t id)
{
int err = 0;
struct inode *inode;
struct inode *lower_inode;
struct super_block *lower_sb;
struct dentry *ret_dentry;
lower_inode = d_inode(lower_path->dentry);
lower_sb = sdcardfs_lower_super(sb);
/* check that the lower file system didn't cross a mount point */
if (lower_inode->i_sb != lower_sb) {
err = -EXDEV;
ret_dentry = ERR_PTR(-EXDEV);
goto out;
}
@ -196,14 +194,32 @@ int sdcardfs_interpose(struct dentry *dentry, struct super_block *sb,
/* inherit lower inode number for sdcardfs's inode */
inode = sdcardfs_iget(sb, lower_inode, id);
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
ret_dentry = ERR_CAST(inode);
goto out;
}
d_add(dentry, inode);
ret_dentry = d_splice_alias(inode, dentry);
dentry = ret_dentry ?: dentry;
update_derived_permission_lock(dentry);
out:
return err;
return ret_dentry;
}
/*
* Connect an sdcardfs inode dentry/inode with several lower ones. This is
* the classic stackable file system "vnode interposition" action.
*
* @dentry: sdcardfs's dentry which interposes on lower one
* @sb: sdcardfs's super_block
* @lower_path: the lower path (caller does path_get/put)
*/
int sdcardfs_interpose(struct dentry *dentry, struct super_block *sb,
struct path *lower_path, userid_t id)
{
struct dentry *ret_dentry;
ret_dentry = __sdcardfs_interpose(dentry, sb, lower_path, id);
return PTR_ERR(ret_dentry);
}
struct sdcardfs_name_data {
@ -244,6 +260,7 @@ static struct dentry *__sdcardfs_lookup(struct dentry *dentry,
const struct qstr *name;
struct path lower_path;
struct qstr dname;
struct dentry *ret_dentry = NULL;
struct sdcardfs_sb_info *sbi;
sbi = SDCARDFS_SB(dentry->d_sb);
@ -330,9 +347,13 @@ static struct dentry *__sdcardfs_lookup(struct dentry *dentry,
}
sdcardfs_set_lower_path(dentry, &lower_path);
err = sdcardfs_interpose(dentry, dentry->d_sb, &lower_path, id);
if (err) /* path_put underlying path on error */
ret_dentry =
__sdcardfs_interpose(dentry, dentry->d_sb, &lower_path, id);
if (IS_ERR(ret_dentry)) {
err = PTR_ERR(ret_dentry);
/* path_put underlying path on error */
sdcardfs_put_reset_lower_path(dentry);
}
goto out;
}
@ -372,7 +393,9 @@ static struct dentry *__sdcardfs_lookup(struct dentry *dentry,
err = 0;
out:
return ERR_PTR(err);
if (err)
return ERR_PTR(err);
return ret_dentry;
}
/*