forked from rubenslte/android_kernel_samsung_msm8226
David Herrmann
ff0e03d3f4
memfd_create() is similar to mmap(MAP_ANON), but returns a file-descriptor that you can pass to mmap(). It can support sealing and avoids any connection to user-visible mount-points. Thus, it's not subject to quotas on mounted file-systems, but can be used like malloc()'ed memory, but with a file-descriptor to it. memfd_create() returns the raw shmem file, so calls like ftruncate() can be used to modify the underlying inode. Also calls like fstat() will return proper information and mark the file as regular file. If you want sealing, you can specify MFD_ALLOW_SEALING. Otherwise, sealing is not supported (like on all other regular files). Compared to O_TMPFILE, it does not require a tmpfs mount-point and is not subject to a filesystem size limit. It is still properly accounted to memcg limits, though, and to the same overcommit or no-overcommit accounting as all user memory. Change-Id: Id7f5dc15f3dcca8e0e8e5d9aea4a9b53cad6a769 Signed-off-by: David Herrmann <dh.herrmann@gmail.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Ryan Lortie <desrt@desrt.ca> Cc: Lennart Poettering <lennart@poettering.net> Cc: Daniel Mack <zonque@gmail.com> Cc: Andy Lutomirski <luto@amacapital.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
9 lines
186 B
C
9 lines
186 B
C
#ifndef _LINUX_MEMFD_H
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#define _LINUX_MEMFD_H
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/* flags for memfd_create(2) (unsigned int) */
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#define MFD_CLOEXEC 0x0001U
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#define MFD_ALLOW_SEALING 0x0002U
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#endif /* _LINUX_MEMFD_H */
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