diff options
Diffstat (limited to 'include/linux/fs.h')
| -rw-r--r-- | include/linux/fs.h | 29 |
1 files changed, 27 insertions, 2 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h index 1ab6c6913040..f0890e4a7c25 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); } /* |