diff options
| -rw-r--r-- | Documentation/filesystems/locking.rst | 2 | ||||
| -rw-r--r-- | Documentation/filesystems/vfs.rst | 16 | ||||
| -rw-r--r-- | fs/overlayfs/super.c | 52 | ||||
| -rw-r--r-- | include/linux/dcache.h | 18 |
4 files changed, 41 insertions, 47 deletions
diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst index d5bf4b6b7509..e664061ed55d 100644 --- a/Documentation/filesystems/locking.rst +++ b/Documentation/filesystems/locking.rst @@ -29,7 +29,7 @@ prototypes:: char *(*d_dname)((struct dentry *dentry, char *buffer, int buflen); struct vfsmount *(*d_automount)(struct path *path); int (*d_manage)(const struct path *, bool); - struct dentry *(*d_real)(struct dentry *, const struct inode *); + struct dentry *(*d_real)(struct dentry *, enum d_real_type type); locking rules: diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst index eebcc0f9e2bc..6e903a903f8f 100644 --- a/Documentation/filesystems/vfs.rst +++ b/Documentation/filesystems/vfs.rst @@ -1264,7 +1264,7 @@ defined: char *(*d_dname)(struct dentry *, char *, int); struct vfsmount *(*d_automount)(struct path *); int (*d_manage)(const struct path *, bool); - struct dentry *(*d_real)(struct dentry *, const struct inode *); + struct dentry *(*d_real)(struct dentry *, enum d_real_type type); }; ``d_revalidate`` @@ -1419,16 +1419,14 @@ defined: the dentry being transited from. ``d_real`` - overlay/union type filesystems implement this method to return - one of the underlying dentries hidden by the overlay. It is - used in two different modes: + overlay/union type filesystems implement this method to return one + of the underlying dentries of a regular file hidden by the overlay. - Called from file_dentry() it returns the real dentry matching - the inode argument. The real dentry may be from a lower layer - already copied up, but still referenced from the file. This - mode is selected with a non-NULL inode argument. + The 'type' argument takes the values D_REAL_DATA or D_REAL_METADATA + for returning the real underlying dentry that refers to the inode + hosting the file's data or metadata respectively. - With NULL inode the topmost real underlying dentry is returned. + For non-regular files, the 'dentry' argument is returned. Each dentry has a pointer to its parent dentry, as well as a hash list of child dentries. Child dentries are basically like files in a diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 4ab66e3d4cff..df2ad2f60798 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -28,41 +28,38 @@ MODULE_LICENSE("GPL"); struct ovl_dir_cache; -static struct dentry *ovl_d_real(struct dentry *dentry, - const struct inode *inode) +static struct dentry *ovl_d_real(struct dentry *dentry, enum d_real_type type) { - struct dentry *real = NULL, *lower; + struct dentry *upper, *lower; int err; - /* - * vfs is only expected to call d_real() with NULL from d_real_inode() - * and with overlay inode from file_dentry() on an overlay file. - * - * TODO: remove @inode argument from d_real() API, remove code in this - * function that deals with non-NULL @inode and remove d_real() call - * from file_dentry(). - */ - if (inode && d_inode(dentry) == inode) - return dentry; - else if (inode) + switch (type) { + case D_REAL_DATA: + case D_REAL_METADATA: + break; + default: goto bug; + } if (!d_is_reg(dentry)) { /* d_real_inode() is only relevant for regular files */ return dentry; } - real = ovl_dentry_upper(dentry); - if (real && (inode == d_inode(real))) - return real; + upper = ovl_dentry_upper(dentry); + if (upper && (type == D_REAL_METADATA || + ovl_has_upperdata(d_inode(dentry)))) + return upper; - if (real && !inode && ovl_has_upperdata(d_inode(dentry))) - return real; + if (type == D_REAL_METADATA) { + lower = ovl_dentry_lower(dentry); + goto real_lower; + } /* - * Best effort lazy lookup of lowerdata for !inode case to return + * Best effort lazy lookup of lowerdata for D_REAL_DATA 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 + * D_REAL_DATA 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. @@ -73,18 +70,13 @@ static struct dentry *ovl_d_real(struct dentry *dentry, lower = ovl_dentry_lowerdata(dentry); if (!lower) goto bug; - real = lower; - /* Handle recursion */ - real = d_real(real, inode); +real_lower: + /* Handle recursion into stacked lower fs */ + return d_real(lower, type); - if (!inode || inode == d_inode(real)) - return real; bug: - WARN(1, "%s(%pd4, %s:%lu): real dentry (%p/%lu) not found\n", - __func__, dentry, inode ? inode->i_sb->s_id : "NULL", - inode ? inode->i_ino : 0, real, - real && d_inode(real) ? d_inode(real)->i_ino : 0); + WARN(1, "%s(%pd4, %d): real dentry not found\n", __func__, dentry, type); return dentry; } diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 1666c387861f..d616a745a34c 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -125,6 +125,11 @@ enum dentry_d_lock_class DENTRY_D_LOCK_NESTED }; +enum d_real_type { + D_REAL_DATA, + D_REAL_METADATA, +}; + struct dentry_operations { int (*d_revalidate)(struct dentry *, unsigned int); int (*d_weak_revalidate)(struct dentry *, unsigned int); @@ -139,7 +144,7 @@ struct dentry_operations { char *(*d_dname)(struct dentry *, char *, int); struct vfsmount *(*d_automount)(struct path *); int (*d_manage)(const struct path *, bool); - struct dentry *(*d_real)(struct dentry *, const struct inode *); + struct dentry *(*d_real)(struct dentry *, enum d_real_type type); } ____cacheline_aligned; /* @@ -546,24 +551,23 @@ static inline struct inode *d_backing_inode(const struct dentry *upper) /** * d_real - Return the real dentry * @dentry: the dentry to query - * @inode: inode to select the dentry from multiple layers (can be NULL) + * @type: the type of real dentry (data or metadata) * * If dentry is on a union/overlay, then return the underlying, real dentry. * Otherwise return the dentry itself. * * See also: Documentation/filesystems/vfs.rst */ -static inline struct dentry *d_real(struct dentry *dentry, - const struct inode *inode) +static inline struct dentry *d_real(struct dentry *dentry, enum d_real_type type) { if (unlikely(dentry->d_flags & DCACHE_OP_REAL)) - return dentry->d_op->d_real(dentry, inode); + return dentry->d_op->d_real(dentry, type); else return dentry; } /** - * d_real_inode - Return the real inode + * d_real_inode - Return the real inode hosting the data * @dentry: The dentry to query * * If dentry is on a union/overlay, then return the underlying, real inode. @@ -572,7 +576,7 @@ static inline struct dentry *d_real(struct dentry *dentry, static inline struct inode *d_real_inode(const struct dentry *dentry) { /* This usage of d_real() results in const dentry */ - return d_backing_inode(d_real((struct dentry *) dentry, NULL)); + return d_inode(d_real((struct dentry *) dentry, D_REAL_DATA)); } struct name_snapshot { |