From 25b7713afe50963e70f98c1c964f60baf1e7e373 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 4 Jul 2017 22:03:16 +0200 Subject: [PATCH] ovl: use i_private only as a key Signed-off-by: Miklos Szeredi --- fs/overlayfs/inode.c | 4 ++-- fs/overlayfs/overlayfs.h | 13 +------------ fs/overlayfs/ovl_entry.h | 2 ++ fs/overlayfs/super.c | 3 +++ fs/overlayfs/util.c | 35 +++++++++++++++++++++++++++++------ 5 files changed, 37 insertions(+), 20 deletions(-) diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index 22c677040b35..4c30d44905ef 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -453,12 +453,12 @@ struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev) static int ovl_inode_test(struct inode *inode, void *data) { - return ovl_inode_real(inode, NULL) == data; + return inode->i_private == data; } static int ovl_inode_set(struct inode *inode, void *data) { - inode->i_private = (void *) (((unsigned long) data) | OVL_ISUPPER_MASK); + inode->i_private = data; return 0; } diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index 3af33d3166e2..6e6600ae1d54 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -60,8 +60,6 @@ struct ovl_fh { u8 fid[0]; /* file identifier */ } __packed; -#define OVL_ISUPPER_MASK 1UL - static inline int ovl_do_rmdir(struct inode *dir, struct dentry *dentry) { int err = vfs_rmdir(dir, dentry); @@ -175,16 +173,6 @@ static inline struct dentry *ovl_do_tmpfile(struct dentry *dentry, umode_t mode) return ret; } -static inline struct inode *ovl_inode_real(struct inode *inode, bool *is_upper) -{ - unsigned long x = (unsigned long) READ_ONCE(inode->i_private); - - if (is_upper) - *is_upper = x & OVL_ISUPPER_MASK; - - return (struct inode *) (x & ~OVL_ISUPPER_MASK); -} - /* util.c */ int ovl_want_write(struct dentry *dentry); void ovl_drop_write(struct dentry *dentry); @@ -201,6 +189,7 @@ 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 dentry *ovl_dentry_real(struct dentry *dentry); +struct inode *ovl_inode_real(struct inode *inode, bool *is_upper); struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry); void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache); bool ovl_dentry_is_opaque(struct dentry *dentry); diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h index 553727df886c..b8c213891e84 100644 --- a/fs/overlayfs/ovl_entry.h +++ b/fs/overlayfs/ovl_entry.h @@ -61,6 +61,8 @@ static inline struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe) struct ovl_inode { struct inode vfs_inode; + struct inode *upper; + struct inode *lower; }; static inline struct ovl_inode *OVL_I(struct inode *inode) diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index ec1b40816483..c166c1d76890 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -171,6 +171,9 @@ static struct inode *ovl_alloc_inode(struct super_block *sb) { struct ovl_inode *oi = kmem_cache_alloc(ovl_inode_cachep, GFP_KERNEL); + oi->upper = NULL; + oi->lower = NULL; + return &oi->vfs_inode; } diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c index f4847eff3284..fc7b1447435b 100644 --- a/fs/overlayfs/util.c +++ b/fs/overlayfs/util.c @@ -155,6 +155,22 @@ struct dentry *ovl_dentry_real(struct dentry *dentry) return realdentry; } +struct inode *ovl_inode_real(struct inode *inode, bool *is_upper) +{ + struct inode *realinode = lockless_dereference(OVL_I(inode)->upper); + bool isup = false; + + if (!realinode) + realinode = OVL_I(inode)->lower; + else + isup = true; + + if (is_upper) + *is_upper = isup; + + return realinode; +} + struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry) { struct ovl_entry *oe = dentry->d_fsdata; @@ -233,10 +249,11 @@ void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry) void ovl_inode_init(struct inode *inode, struct dentry *dentry) { struct inode *realinode = d_inode(ovl_dentry_real(dentry)); - bool is_upper = ovl_dentry_upper(dentry); - WRITE_ONCE(inode->i_private, (unsigned long) realinode | - (is_upper ? OVL_ISUPPER_MASK : 0)); + if (ovl_dentry_upper(dentry)) + OVL_I(inode)->upper = realinode; + else + OVL_I(inode)->lower = realinode; ovl_copyattr(realinode, inode); } @@ -245,10 +262,16 @@ void ovl_inode_update(struct inode *inode, struct inode *upperinode) { WARN_ON(!upperinode); WARN_ON(!inode_unhashed(inode)); - WRITE_ONCE(inode->i_private, - (unsigned long) upperinode | OVL_ISUPPER_MASK); - if (!S_ISDIR(upperinode->i_mode)) + /* + * Make sure upperinode is consistent before making it visible to + * ovl_inode_real(); + */ + smp_wmb(); + OVL_I(inode)->upper = upperinode; + if (!S_ISDIR(upperinode->i_mode)) { + inode->i_private = upperinode; __insert_inode_hash(inode, (unsigned long) upperinode); + } } void ovl_dentry_version_inc(struct dentry *dentry)