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| author | Christoph Hellwig <hch@lst.de> | 2015-01-14 10:42:32 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2015-01-20 14:02:58 -0700 |
| commit | b4caecd48005fbed3949dde6c1cb233142fd69e9 (patch) | |
| tree | 1fdd9b7c15568c79eb3c1ed84a39858ddbcbc88b /include/linux/fs.h | |
| parent | 97b713ba3ebaa6c8d84c2c720f5468a7c6a6eb4e (diff) | |
| download | lwn-b4caecd48005fbed3949dde6c1cb233142fd69e9.tar.gz lwn-b4caecd48005fbed3949dde6c1cb233142fd69e9.zip | |
fs: introduce f_op->mmap_capabilities for nommu mmap support
Since "BDI: Provide backing device capability information [try #3]" the
backing_dev_info structure also provides flags for the kind of mmap
operation available in a nommu environment, which is entirely unrelated
to it's original purpose.
Introduce a new nommu-only file operation to provide this information to
the nommu mmap code instead. Splitting this from the backing_dev_info
structure allows to remove lots of backing_dev_info instance that aren't
otherwise needed, and entirely gets rid of the concept of providing a
backing_dev_info for a character device. It also removes the need for
the mtd_inodefs filesystem.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Tejun Heo <tj@kernel.org>
Acked-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'include/linux/fs.h')
| -rw-r--r-- | include/linux/fs.h | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h index 42efe13077b6..1dada399aa23 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1502,6 +1502,26 @@ struct block_device_operations; #define HAVE_COMPAT_IOCTL 1 #define HAVE_UNLOCKED_IOCTL 1 +/* + * These flags let !MMU mmap() govern direct device mapping vs immediate + * copying more easily for MAP_PRIVATE, especially for ROM filesystems. + * + * NOMMU_MAP_COPY: Copy can be mapped (MAP_PRIVATE) + * NOMMU_MAP_DIRECT: Can be mapped directly (MAP_SHARED) + * NOMMU_MAP_READ: Can be mapped for reading + * NOMMU_MAP_WRITE: Can be mapped for writing + * NOMMU_MAP_EXEC: Can be mapped for execution + */ +#define NOMMU_MAP_COPY 0x00000001 +#define NOMMU_MAP_DIRECT 0x00000008 +#define NOMMU_MAP_READ VM_MAYREAD +#define NOMMU_MAP_WRITE VM_MAYWRITE +#define NOMMU_MAP_EXEC VM_MAYEXEC + +#define NOMMU_VMFLAGS \ + (NOMMU_MAP_READ | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC) + + struct iov_iter; struct file_operations { @@ -1536,6 +1556,9 @@ struct file_operations { long (*fallocate)(struct file *file, int mode, loff_t offset, loff_t len); void (*show_fdinfo)(struct seq_file *m, struct file *f); +#ifndef CONFIG_MMU + unsigned (*mmap_capabilities)(struct file *); +#endif }; struct inode_operations { |