Revision 4ceb5db9757aaeadcf8fbbf97d76bd42aa4df0d6 authored by Linus Torvalds on 01 August 2005, 18:14:49 UTC, committed by Linus Torvalds on 01 August 2005, 18:14:49 UTC
There's no real guarantee that handle_mm_fault() will always be able to break a COW situation - if an update from another thread ends up modifying the page table some way, handle_mm_fault() may end up requiring us to re-try the operation. That's normally fine, but get_user_pages() ended up re-trying it as a read, and thus a write access could in theory end up losing the dirty bit or be done on a page that had not been properly COW'ed. This makes get_user_pages() always retry write accesses as write accesses by making "follow_page()" require that a writable follow has the dirty bit set. That simplifies the code and solves the race: if the COW break fails for some reason, we'll just loop around and try again. Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1 parent 8d894c4
fcntl.h
#ifndef _ASM_FCNTL_H
#define _ASM_FCNTL_H
/* open/fcntl - O_SYNC is only implemented on blocks devices and on files
located on an ext2 file system */
#define O_ACCMODE 0003
#define O_RDONLY 00
#define O_WRONLY 01
#define O_RDWR 02
#define O_CREAT 0100 /* not fcntl */
#define O_EXCL 0200 /* not fcntl */
#define O_NOCTTY 0400 /* not fcntl */
#define O_TRUNC 01000 /* not fcntl */
#define O_APPEND 02000
#define O_NONBLOCK 04000
#define O_NDELAY O_NONBLOCK
#define O_SYNC 010000
#define FASYNC 020000 /* fcntl, for BSD compatibility */
#define O_DIRECT 040000 /* direct disk access hint */
#define O_LARGEFILE 0100000
#define O_DIRECTORY 0200000 /* must be a directory */
#define O_NOFOLLOW 0400000 /* don't follow links */
#define O_NOATIME 01000000
#define F_DUPFD 0 /* dup */
#define F_GETFD 1 /* get close_on_exec */
#define F_SETFD 2 /* set/clear close_on_exec */
#define F_GETFL 3 /* get file->f_flags */
#define F_SETFL 4 /* set file->f_flags */
#define F_GETLK 5
#define F_SETLK 6
#define F_SETLKW 7
#define F_SETOWN 8 /* for sockets. */
#define F_GETOWN 9 /* for sockets. */
#define F_SETSIG 10 /* for sockets. */
#define F_GETSIG 11 /* for sockets. */
#define F_GETLK64 12 /* using 'struct flock64' */
#define F_SETLK64 13
#define F_SETLKW64 14
/* for F_[GET|SET]FL */
#define FD_CLOEXEC 1 /* actually anything with low bit set goes */
/* for posix fcntl() and lockf() */
#define F_RDLCK 0
#define F_WRLCK 1
#define F_UNLCK 2
/* for old implementation of bsd flock () */
#define F_EXLCK 4 /* or 3 */
#define F_SHLCK 8 /* or 4 */
/* for leases */
#define F_INPROGRESS 16
/* operations for bsd flock(), also used by the kernel implementation */
#define LOCK_SH 1 /* shared lock */
#define LOCK_EX 2 /* exclusive lock */
#define LOCK_NB 4 /* or'd with one of the above to prevent
blocking */
#define LOCK_UN 8 /* remove lock */
#define LOCK_MAND 32 /* This is a mandatory flock */
#define LOCK_READ 64 /* ... Which allows concurrent read operations */
#define LOCK_WRITE 128 /* ... Which allows concurrent write operations */
#define LOCK_RW 192 /* ... Which allows concurrent read & write ops */
struct flock {
short l_type;
short l_whence;
off_t l_start;
off_t l_len;
pid_t l_pid;
};
struct flock64 {
short l_type;
short l_whence;
loff_t l_start;
loff_t l_len;
pid_t l_pid;
};
#define F_LINUX_SPECIFIC_BASE 1024
#endif /* _ASM_FCNTL_H */
![swh spinner](/static/img/swh-spinner.gif)
Computing file changes ...