Documentation/filesystems/mandatory-locking.rst

25 	  the kernel has decided to proceed with a read, but before the
51 with a "mandatory" locking scheme, whereby the operating system kernel would
85 to run mandatory lock candidates with setgid privileges.
90 I have considered the implementations of mandatory locking available with
98 contravention of SVID 3, which states that only calls to open() with the
100 definition, which is the "Right Thing", since only calls with O_TRUNC can
103 HP-UX even disallows open() with O_TRUNC for a file with advisory locks, not
129 2. If a process has locked a region of a file with a mandatory read lock, then
132    released, unless the process has opened the file with the O_NONBLOCK
133    flag in which case the system call will return immediately with the error
136 3. If a process has locked a region of a file with a mandatory write lock, all
138    unless a process has opened the file with the O_NONBLOCK flag in which case
139    the system call will return immediately with the error status EAGAIN.
141 4. Calls to open() with O_TRUNC, or to creat(), on a existing file that has
142    any mandatory locks owned by other processes will be rejected with the
146    shared (via mmap() with MAP_SHARED) will be rejected with the error status
149 6. Attempts to create a shared memory map of a file (via mmap() with MAP_SHARED)
150    that has any mandatory locks in effect will be rejected with the error status
182 administratively enabled by mounting with "-o mand". That mount option
187 with this disabled will reject attempts to mount filesystems with the
188 "mand" mount option with the error status EPERM.