From c2b3e74b78b24cb367289a75a2bd30e569e56e0e Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 13 Dec 2010 19:38:08 -0500 Subject: fs: Remove unlikely() from fput_light() In fput_light(), there's an unlikely(fput_needed), which running on my normal desktop doing firefox, xchat, evolution and part of my distcc farm, and running the annotate branch profiler shows that the unlikely is not very unlikely. correct incorrect % Function File Line ------- --------- - -------- ---- ---- 0 48 100 fput_light file.h 26 115828710 897415279 88 fput_light file.h 26 865271179 5286128445 85 fput_light file.h 26 19568539 8923664 31 fput_light file.h 26 12353677 3562279 22 fput_light file.h 26 267691 67062 20 fput_light file.h 26 15014853 348172 2 fput_light file.h 26 209258 205 0 fput_light file.h 26 1364164 0 0 fput_light file.h 26 Which gives 1032903812 times it was correct and 6203351846 times it was incorrect, or 85% incorrect. Cc: Andrew Morton Signed-off-by: Steven Rostedt Signed-off-by: Al Viro --- include/linux/file.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/file.h') diff --git a/include/linux/file.h b/include/linux/file.h index b1e12970f617..e85baebf6279 100644 --- a/include/linux/file.h +++ b/include/linux/file.h @@ -23,7 +23,7 @@ extern struct file *alloc_file(struct path *, fmode_t mode, static inline void fput_light(struct file *file, int fput_needed) { - if (unlikely(fput_needed)) + if (fput_needed) fput(file); } -- cgit v1.2.2 From 1abf0c718f15a56a0a435588d1b104c7a37dc9bd Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sun, 13 Mar 2011 03:51:11 -0400 Subject: New kind of open files - "location only". New flag for open(2) - O_PATH. Semantics: * pathname is resolved, but the file itself is _NOT_ opened as far as filesystem is concerned. * almost all operations on the resulting descriptors shall fail with -EBADF. Exceptions are: 1) operations on descriptors themselves (i.e. close(), dup(), dup2(), dup3(), fcntl(fd, F_DUPFD), fcntl(fd, F_DUPFD_CLOEXEC, ...), fcntl(fd, F_GETFD), fcntl(fd, F_SETFD, ...)) 2) fcntl(fd, F_GETFL), for a common non-destructive way to check if descriptor is open 3) "dfd" arguments of ...at(2) syscalls, i.e. the starting points of pathname resolution * closing such descriptor does *NOT* affect dnotify or posix locks. * permissions are checked as usual along the way to file; no permission checks are applied to the file itself. Of course, giving such thing to syscall will result in permission checks (at the moment it means checking that starting point of ....at() is a directory and caller has exec permissions on it). fget() and fget_light() return NULL on such descriptors; use of fget_raw() and fget_raw_light() is needed to get them. That protects existing code from dealing with those things. There are two things still missing (they come in the next commits): one is handling of symlinks (right now we refuse to open them that way; see the next commit for semantics related to those) and another is descriptor passing via SCM_RIGHTS datagrams. Signed-off-by: Al Viro --- include/linux/file.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/file.h') diff --git a/include/linux/file.h b/include/linux/file.h index e85baebf6279..21a79958541c 100644 --- a/include/linux/file.h +++ b/include/linux/file.h @@ -29,6 +29,8 @@ static inline void fput_light(struct file *file, int fput_needed) extern struct file *fget(unsigned int fd); extern struct file *fget_light(unsigned int fd, int *fput_needed); +extern struct file *fget_raw(unsigned int fd); +extern struct file *fget_raw_light(unsigned int fd, int *fput_needed); extern void set_close_on_exec(unsigned int fd, int flag); extern void put_filp(struct file *); extern int alloc_fd(unsigned start, unsigned flags); -- cgit v1.2.2