This is a note to let you know that I've just added the patch titled fs: add file_dentry() to the 4.5-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: fs-add-file_dentry.patch and it can be found in the queue-4.5 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From d101a125954eae1d397adda94ca6319485a50493 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi <miklos@xxxxxxxxxx> Date: Sat, 26 Mar 2016 16:14:37 -0400 Subject: fs: add file_dentry() From: Miklos Szeredi <miklos@xxxxxxxxxx> commit d101a125954eae1d397adda94ca6319485a50493 upstream. This series fixes bugs in nfs and ext4 due to 4bacc9c9234c ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay"). Regular files opened on overlayfs will result in the file being opened on the underlying filesystem, while f_path points to the overlayfs mount/dentry. This confuses filesystems which get the dentry from struct file and assume it's theirs. Add a new helper, file_dentry() [*], to get the filesystem's own dentry from the file. This checks file->f_path.dentry->d_flags against DCACHE_OP_REAL, and returns file->f_path.dentry if DCACHE_OP_REAL is not set (this is the common, non-overlayfs case). In the uncommon case it will call into overlayfs's ->d_real() to get the underlying dentry, matching file_inode(file). The reason we need to check against the inode is that if the file is copied up while being open, d_real() would return the upper dentry, while the open file comes from the lower dentry. [*] If possible, it's better simply to use file_inode() instead. Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx> Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Tested-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx> Reviewed-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> Cc: David Howells <dhowells@xxxxxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Daniel Axtens <dja@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/dcache.c | 5 ++++- fs/overlayfs/super.c | 33 +++++++++++++++++++++++++++++++++ include/linux/dcache.h | 10 ++++++++++ include/linux/fs.h | 10 ++++++++++ 4 files changed, 57 insertions(+), 1 deletion(-) --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1667,7 +1667,8 @@ void d_set_d_op(struct dentry *dentry, c DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE | DCACHE_OP_DELETE | - DCACHE_OP_SELECT_INODE)); + DCACHE_OP_SELECT_INODE | + DCACHE_OP_REAL)); dentry->d_op = op; if (!op) return; @@ -1685,6 +1686,8 @@ void d_set_d_op(struct dentry *dentry, c dentry->d_flags |= DCACHE_OP_PRUNE; if (op->d_select_inode) dentry->d_flags |= DCACHE_OP_SELECT_INODE; + if (op->d_real) + dentry->d_flags |= DCACHE_OP_REAL; } EXPORT_SYMBOL(d_set_d_op); --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -295,6 +295,37 @@ static void ovl_dentry_release(struct de } } +static struct dentry *ovl_d_real(struct dentry *dentry, struct inode *inode) +{ + struct dentry *real; + + if (d_is_dir(dentry)) { + if (!inode || inode == d_inode(dentry)) + return dentry; + goto bug; + } + + real = ovl_dentry_upper(dentry); + if (real && (!inode || inode == d_inode(real))) + return real; + + real = ovl_dentry_lower(dentry); + if (!real) + goto bug; + + if (!inode || inode == d_inode(real)) + return real; + + /* Handle recursion */ + if (real->d_flags & DCACHE_OP_REAL) + return real->d_op->d_real(real, inode); + +bug: + WARN(1, "ovl_d_real(%pd4, %s:%lu\n): real dentry not found\n", dentry, + inode ? inode->i_sb->s_id : "NULL", inode ? inode->i_ino : 0); + return dentry; +} + static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags) { struct ovl_entry *oe = dentry->d_fsdata; @@ -339,11 +370,13 @@ static int ovl_dentry_weak_revalidate(st static const struct dentry_operations ovl_dentry_operations = { .d_release = ovl_dentry_release, .d_select_inode = ovl_d_select_inode, + .d_real = ovl_d_real, }; static const struct dentry_operations ovl_reval_dentry_operations = { .d_release = ovl_dentry_release, .d_select_inode = ovl_d_select_inode, + .d_real = ovl_d_real, .d_revalidate = ovl_dentry_revalidate, .d_weak_revalidate = ovl_dentry_weak_revalidate, }; --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -161,6 +161,7 @@ struct dentry_operations { struct vfsmount *(*d_automount)(struct path *); int (*d_manage)(struct dentry *, bool); struct inode *(*d_select_inode)(struct dentry *, unsigned); + struct dentry *(*d_real)(struct dentry *, struct inode *); } ____cacheline_aligned; /* @@ -227,6 +228,7 @@ struct dentry_operations { #define DCACHE_MAY_FREE 0x00800000 #define DCACHE_FALLTHRU 0x01000000 /* Fall through to lower layer */ #define DCACHE_OP_SELECT_INODE 0x02000000 /* Unioned entry: dcache op selects inode */ +#define DCACHE_OP_REAL 0x08000000 extern seqlock_t rename_lock; @@ -582,4 +584,12 @@ static inline struct dentry *d_backing_d return upper; } +static inline struct dentry *d_real(struct dentry *dentry) +{ + if (unlikely(dentry->d_flags & DCACHE_OP_REAL)) + return dentry->d_op->d_real(dentry, NULL); + else + return dentry; +} + #endif /* __LINUX_DCACHE_H */ --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1234,6 +1234,16 @@ static inline struct inode *file_inode(c return f->f_inode; } +static inline struct dentry *file_dentry(const struct file *file) +{ + struct dentry *dentry = file->f_path.dentry; + + if (unlikely(dentry->d_flags & DCACHE_OP_REAL)) + return dentry->d_op->d_real(dentry, file_inode(file)); + else + return dentry; +} + static inline int locks_lock_file_wait(struct file *filp, struct file_lock *fl) { return locks_lock_inode_wait(file_inode(filp), fl); Patches currently in stable-queue which might be from miklos@xxxxxxxxxx are queue-4.5/fs-add-file_dentry.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html