mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-04 01:49:36 +00:00
![Jan Kara](/assets/img/avatar_default.png)
Doing iput() from flusher thread (writeback_sb_inodes()) can create problems because iput() can do a lot of work - for example truncate the inode if it's the last iput on unlinked file. Some filesystems depend on flusher thread progressing (e.g. because they need to flush delay allocated blocks to reduce allocation uncertainty) and so flusher thread doing truncate creates interesting dependencies and possibilities for deadlocks. We get rid of iput() in flusher thread by using the fact that I_SYNC inode flag effectively pins the inode in memory. So if we take care to either hold i_lock or have I_SYNC set, we can get away without taking inode reference in writeback_sb_inodes(). As a side effect of these changes, we also fix possible use-after-free in wb_writeback() because inode_wait_for_writeback() call could try to reacquire i_lock on the inode that was already free. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
197 lines
6.2 KiB
C
197 lines
6.2 KiB
C
/*
|
|
* include/linux/writeback.h
|
|
*/
|
|
#ifndef WRITEBACK_H
|
|
#define WRITEBACK_H
|
|
|
|
#include <linux/sched.h>
|
|
#include <linux/fs.h>
|
|
|
|
DECLARE_PER_CPU(int, dirty_throttle_leaks);
|
|
|
|
/*
|
|
* The 1/4 region under the global dirty thresh is for smooth dirty throttling:
|
|
*
|
|
* (thresh - thresh/DIRTY_FULL_SCOPE, thresh)
|
|
*
|
|
* Further beyond, all dirtier tasks will enter a loop waiting (possibly long
|
|
* time) for the dirty pages to drop, unless written enough pages.
|
|
*
|
|
* The global dirty threshold is normally equal to the global dirty limit,
|
|
* except when the system suddenly allocates a lot of anonymous memory and
|
|
* knocks down the global dirty threshold quickly, in which case the global
|
|
* dirty limit will follow down slowly to prevent livelocking all dirtier tasks.
|
|
*/
|
|
#define DIRTY_SCOPE 8
|
|
#define DIRTY_FULL_SCOPE (DIRTY_SCOPE / 2)
|
|
|
|
struct backing_dev_info;
|
|
|
|
/*
|
|
* fs/fs-writeback.c
|
|
*/
|
|
enum writeback_sync_modes {
|
|
WB_SYNC_NONE, /* Don't wait on anything */
|
|
WB_SYNC_ALL, /* Wait on every mapping */
|
|
};
|
|
|
|
/*
|
|
* why some writeback work was initiated
|
|
*/
|
|
enum wb_reason {
|
|
WB_REASON_BACKGROUND,
|
|
WB_REASON_TRY_TO_FREE_PAGES,
|
|
WB_REASON_SYNC,
|
|
WB_REASON_PERIODIC,
|
|
WB_REASON_LAPTOP_TIMER,
|
|
WB_REASON_FREE_MORE_MEM,
|
|
WB_REASON_FS_FREE_SPACE,
|
|
WB_REASON_FORKER_THREAD,
|
|
|
|
WB_REASON_MAX,
|
|
};
|
|
extern const char *wb_reason_name[];
|
|
|
|
/*
|
|
* A control structure which tells the writeback code what to do. These are
|
|
* always on the stack, and hence need no locking. They are always initialised
|
|
* in a manner such that unspecified fields are set to zero.
|
|
*/
|
|
struct writeback_control {
|
|
long nr_to_write; /* Write this many pages, and decrement
|
|
this for each page written */
|
|
long pages_skipped; /* Pages which were not written */
|
|
|
|
/*
|
|
* For a_ops->writepages(): if start or end are non-zero then this is
|
|
* a hint that the filesystem need only write out the pages inside that
|
|
* byterange. The byte at `end' is included in the writeout request.
|
|
*/
|
|
loff_t range_start;
|
|
loff_t range_end;
|
|
|
|
enum writeback_sync_modes sync_mode;
|
|
|
|
unsigned for_kupdate:1; /* A kupdate writeback */
|
|
unsigned for_background:1; /* A background writeback */
|
|
unsigned tagged_writepages:1; /* tag-and-write to avoid livelock */
|
|
unsigned for_reclaim:1; /* Invoked from the page allocator */
|
|
unsigned range_cyclic:1; /* range_start is cyclic */
|
|
};
|
|
|
|
/*
|
|
* fs/fs-writeback.c
|
|
*/
|
|
struct bdi_writeback;
|
|
int inode_wait(void *);
|
|
void writeback_inodes_sb(struct super_block *, enum wb_reason reason);
|
|
void writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
|
|
enum wb_reason reason);
|
|
int writeback_inodes_sb_if_idle(struct super_block *, enum wb_reason reason);
|
|
int writeback_inodes_sb_nr_if_idle(struct super_block *, unsigned long nr,
|
|
enum wb_reason reason);
|
|
void sync_inodes_sb(struct super_block *);
|
|
long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages,
|
|
enum wb_reason reason);
|
|
long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
|
|
void wakeup_flusher_threads(long nr_pages, enum wb_reason reason);
|
|
void inode_wait_for_writeback(struct inode *inode);
|
|
|
|
/* writeback.h requires fs.h; it, too, is not included from here. */
|
|
static inline void wait_on_inode(struct inode *inode)
|
|
{
|
|
might_sleep();
|
|
wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
|
|
}
|
|
|
|
|
|
/*
|
|
* mm/page-writeback.c
|
|
*/
|
|
#ifdef CONFIG_BLOCK
|
|
void laptop_io_completion(struct backing_dev_info *info);
|
|
void laptop_sync_completion(void);
|
|
void laptop_mode_sync(struct work_struct *work);
|
|
void laptop_mode_timer_fn(unsigned long data);
|
|
#else
|
|
static inline void laptop_sync_completion(void) { }
|
|
#endif
|
|
void throttle_vm_writeout(gfp_t gfp_mask);
|
|
bool zone_dirty_ok(struct zone *zone);
|
|
|
|
extern unsigned long global_dirty_limit;
|
|
|
|
/* These are exported to sysctl. */
|
|
extern int dirty_background_ratio;
|
|
extern unsigned long dirty_background_bytes;
|
|
extern int vm_dirty_ratio;
|
|
extern unsigned long vm_dirty_bytes;
|
|
extern unsigned int dirty_writeback_interval;
|
|
extern unsigned int dirty_expire_interval;
|
|
extern int vm_highmem_is_dirtyable;
|
|
extern int block_dump;
|
|
extern int laptop_mode;
|
|
|
|
extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
|
|
void __user *buffer, size_t *lenp,
|
|
loff_t *ppos);
|
|
extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
|
|
void __user *buffer, size_t *lenp,
|
|
loff_t *ppos);
|
|
extern int dirty_ratio_handler(struct ctl_table *table, int write,
|
|
void __user *buffer, size_t *lenp,
|
|
loff_t *ppos);
|
|
extern int dirty_bytes_handler(struct ctl_table *table, int write,
|
|
void __user *buffer, size_t *lenp,
|
|
loff_t *ppos);
|
|
|
|
struct ctl_table;
|
|
int dirty_writeback_centisecs_handler(struct ctl_table *, int,
|
|
void __user *, size_t *, loff_t *);
|
|
|
|
void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty);
|
|
unsigned long bdi_dirty_limit(struct backing_dev_info *bdi,
|
|
unsigned long dirty);
|
|
|
|
void __bdi_update_bandwidth(struct backing_dev_info *bdi,
|
|
unsigned long thresh,
|
|
unsigned long bg_thresh,
|
|
unsigned long dirty,
|
|
unsigned long bdi_thresh,
|
|
unsigned long bdi_dirty,
|
|
unsigned long start_time);
|
|
|
|
void page_writeback_init(void);
|
|
void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
|
|
unsigned long nr_pages_dirtied);
|
|
|
|
static inline void
|
|
balance_dirty_pages_ratelimited(struct address_space *mapping)
|
|
{
|
|
balance_dirty_pages_ratelimited_nr(mapping, 1);
|
|
}
|
|
|
|
typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
|
|
void *data);
|
|
|
|
int generic_writepages(struct address_space *mapping,
|
|
struct writeback_control *wbc);
|
|
void tag_pages_for_writeback(struct address_space *mapping,
|
|
pgoff_t start, pgoff_t end);
|
|
int write_cache_pages(struct address_space *mapping,
|
|
struct writeback_control *wbc, writepage_t writepage,
|
|
void *data);
|
|
int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
|
|
void set_page_dirty_balance(struct page *page, int page_mkwrite);
|
|
void writeback_set_ratelimit(void);
|
|
void tag_pages_for_writeback(struct address_space *mapping,
|
|
pgoff_t start, pgoff_t end);
|
|
|
|
void account_page_redirty(struct page *page);
|
|
|
|
/* pdflush.c */
|
|
extern int nr_pdflush_threads; /* Global so it can be exported to sysctl
|
|
read-only. */
|
|
|
|
|
|
#endif /* WRITEBACK_H */
|