[PATCH man-pages] open.2: improve O_PATH documentation.
From: NeilBrown <hidden>
Date: 2017-08-10 03:25:33
Also in:
linux-fsdevel
Subsystem:
the rest · Maintainer:
Linus Torvalds
- fstatfs is now permitted. - ioctl isn't, and is worth listing explicitly - O_PATH allows an automount point to be opened with triggering the mount. All tested Signed-off-by: NeilBrown <neilb-IBi9RG/b67k@public.gmane.org> --- man2/open.2 | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/man2/open.2 b/man2/open.2
index e3b00939790c..38d532397b02 100644
--- a/man2/open.2
+++ b/man2/open.2@@ -585,6 +585,7 @@ The file itself is not opened, and other file operations (e.g., .BR fchmod (2), .BR fchown (2), .BR fgetxattr (2), +.BR ioctl (2), .BR mmap (2)) fail with the error .BR EBADF .
@@ -599,8 +600,11 @@ be performed on the resulting file descriptor: (since Linux 3.5); .\" commit 332a2e1244bd08b9e3ecd378028513396a004a24 .BR fstat (2) -(since Linux 3.6). +(since Linux 3.6); .\" fstat(): commit 55815f70147dcfa3ead5738fd56d3574e2e3c1c2 +.BR fstatfs (2) +(since Linux 3.12). +.\" fstatfs(): commit 9d05746e7b16d8565dddbe3200faa1e669d23bbf .IP * Duplicating the file descriptor .RB ( dup (2),
@@ -666,6 +670,16 @@ argument in calls to and .BR readlinkat (2) with an empty pathname to have the calls operate on the symbolic link. + +If +.I pathname +refers to an automount point that has not yet been triggered, so no +other filesystem is mounted on it, then the call returns a file +descriptor referring to the automount directory without triggering a mount. +.BR fstatfs (2) +can then be used to determine if it is, in fact, an untriggered +automount point +.RB ( ".f_type == AUTOFS_SUPER_MAGIC" ). .TP .B O_SYNC Write operations on the file will complete according to the requirements of
--
2.14.0.rc0.dirty
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