diff options
Diffstat (limited to 'include/linux/fs.h')
| -rw-r--r-- | include/linux/fs.h | 39 |
1 files changed, 35 insertions, 4 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h index 338e6f758c6..f0890e4a7c2 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -387,7 +387,7 @@ struct address_space { struct inode *host; /* owner: inode, block_device */ struct radix_tree_root page_tree; /* radix tree of all pages */ spinlock_t tree_lock; /* and lock protecting it */ - unsigned int i_mmap_writable;/* count VM_SHARED mappings */ + atomic_t i_mmap_writable;/* count VM_SHARED mappings */ struct rb_root i_mmap; /* tree of private and shared mappings */ struct list_head i_mmap_nonlinear;/*list VM_NONLINEAR mappings */ struct mutex i_mmap_mutex; /* protect tree, count, list */ @@ -470,10 +470,35 @@ static inline int mapping_mapped(struct address_space *mapping) * Note that i_mmap_writable counts all VM_SHARED vmas: do_mmap_pgoff * marks vma as VM_SHARED if it is shared, and the file was opened for * writing i.e. vma may be mprotected writable even if now readonly. + * + * If i_mmap_writable is negative, no new writable mappings are allowed. You + * can only deny writable mappings, if none exists right now. */ static inline int mapping_writably_mapped(struct address_space *mapping) { - return mapping->i_mmap_writable != 0; + return atomic_read(&mapping->i_mmap_writable) > 0; +} + +static inline int mapping_map_writable(struct address_space *mapping) +{ + return atomic_inc_unless_negative(&mapping->i_mmap_writable) ? + 0 : -EPERM; +} + +static inline void mapping_unmap_writable(struct address_space *mapping) +{ + atomic_dec(&mapping->i_mmap_writable); +} + +static inline int mapping_deny_writable(struct address_space *mapping) +{ + return atomic_dec_unless_positive(&mapping->i_mmap_writable) ? + 0 : -EBUSY; +} + +static inline void mapping_allow_writable(struct address_space *mapping) +{ + atomic_inc(&mapping->i_mmap_writable); } /* @@ -833,7 +858,7 @@ static inline struct file *get_file(struct file *f) * * Lockd stuffs a "host" pointer into this. */ -typedef struct files_struct *fl_owner_t; +typedef void *fl_owner_t; struct file_lock_operations { void (*fl_copy_lock)(struct file_lock *, struct file_lock *); @@ -1921,6 +1946,12 @@ static inline int break_lease(struct inode *inode, unsigned int mode) static inline int break_deleg(struct inode *inode, unsigned int mode) { + /* + * Since this check is lockless, we must ensure that any refcounts + * taken are done before checking inode->i_flock. Otherwise, we could + * end up racing with tasks trying to set a new lease on this file. + */ + smp_mb(); if (inode->i_flock) return __break_lease(inode, mode, FL_DELEG); return 0; @@ -2682,7 +2713,7 @@ static const struct file_operations __fops = { \ .read = simple_attr_read, \ .write = simple_attr_write, \ .llseek = generic_file_llseek, \ -}; +} static inline __printf(1, 2) void __simple_attr_check_format(const char *fmt, ...) |