diff options
Diffstat (limited to 'include/linux/backing-dev.h')
| -rw-r--r-- | include/linux/backing-dev.h | 104 |
1 files changed, 104 insertions, 0 deletions
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h new file mode 100644 index 00000000000..f7a1390d67f --- /dev/null +++ b/include/linux/backing-dev.h @@ -0,0 +1,104 @@ +/* + * include/linux/backing-dev.h + * + * low-level device information and state which is propagated up through + * to high-level code. + */ + +#ifndef _LINUX_BACKING_DEV_H +#define _LINUX_BACKING_DEV_H + +#include <asm/atomic.h> + +/* + * Bits in backing_dev_info.state + */ +enum bdi_state { + BDI_pdflush, /* A pdflush thread is working this device */ + BDI_write_congested, /* The write queue is getting full */ + BDI_read_congested, /* The read queue is getting full */ + BDI_unused, /* Available bits start here */ +}; + +typedef int (congested_fn)(void *, int); + +struct backing_dev_info { + unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */ + unsigned long state; /* Always use atomic bitops on this */ + unsigned int capabilities; /* Device capabilities */ + congested_fn *congested_fn; /* Function pointer if device is md/dm */ + void *congested_data; /* Pointer to aux data for congested func */ + void (*unplug_io_fn)(struct backing_dev_info *, struct page *); + void *unplug_io_data; +}; + + +/* + * Flags in backing_dev_info::capability + * - The first two flags control whether dirty pages will contribute to the + * VM's accounting and whether writepages() should be called for dirty pages + * (something that would not, for example, be appropriate for ramfs) + * - These flags let !MMU mmap() govern direct device mapping vs immediate + * copying more easily for MAP_PRIVATE, especially for ROM filesystems + */ +#define BDI_CAP_NO_ACCT_DIRTY 0x00000001 /* Dirty pages shouldn't contribute to accounting */ +#define BDI_CAP_NO_WRITEBACK 0x00000002 /* Don't write pages back */ +#define BDI_CAP_MAP_COPY 0x00000004 /* Copy can be mapped (MAP_PRIVATE) */ +#define BDI_CAP_MAP_DIRECT 0x00000008 /* Can be mapped directly (MAP_SHARED) */ +#define BDI_CAP_READ_MAP 0x00000010 /* Can be mapped for reading */ +#define BDI_CAP_WRITE_MAP 0x00000020 /* Can be mapped for writing */ +#define BDI_CAP_EXEC_MAP 0x00000040 /* Can be mapped for execution */ +#define BDI_CAP_VMFLAGS \ + (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP) + +#if defined(VM_MAYREAD) && \ + (BDI_CAP_READ_MAP != VM_MAYREAD || \ + BDI_CAP_WRITE_MAP != VM_MAYWRITE || \ + BDI_CAP_EXEC_MAP != VM_MAYEXEC) +#error please change backing_dev_info::capabilities flags +#endif + +extern struct backing_dev_info default_backing_dev_info; +void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page); + +int writeback_acquire(struct backing_dev_info *bdi); +int writeback_in_progress(struct backing_dev_info *bdi); +void writeback_release(struct backing_dev_info *bdi); + +static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits) +{ + if (bdi->congested_fn) + return bdi->congested_fn(bdi->congested_data, bdi_bits); + return (bdi->state & bdi_bits); +} + +static inline int bdi_read_congested(struct backing_dev_info *bdi) +{ + return bdi_congested(bdi, 1 << BDI_read_congested); +} + +static inline int bdi_write_congested(struct backing_dev_info *bdi) +{ + return bdi_congested(bdi, 1 << BDI_write_congested); +} + +static inline int bdi_rw_congested(struct backing_dev_info *bdi) +{ + return bdi_congested(bdi, (1 << BDI_read_congested)| + (1 << BDI_write_congested)); +} + +#define bdi_cap_writeback_dirty(bdi) \ + (!((bdi)->capabilities & BDI_CAP_NO_WRITEBACK)) + +#define bdi_cap_account_dirty(bdi) \ + (!((bdi)->capabilities & BDI_CAP_NO_ACCT_DIRTY)) + +#define mapping_cap_writeback_dirty(mapping) \ + bdi_cap_writeback_dirty((mapping)->backing_dev_info) + +#define mapping_cap_account_dirty(mapping) \ + bdi_cap_account_dirty((mapping)->backing_dev_info) + + +#endif /* _LINUX_BACKING_DEV_H */ |