| Message ID | 20171023095910.23202-2-marcandre.lureau@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v5,1/6] memfd: split qemu_memfd_alloc() | expand |
On 10/23/2017 06:59 AM, Marc-André Lureau wrote: > Add a function to only create a memfd, without mmap. The function is > used in the following memory backend. > > Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> > --- > include/qemu/memfd.h | 1 + > util/memfd.c | 61 +++++++++++++++++++++++++++++++--------------------- > 2 files changed, 37 insertions(+), 25 deletions(-) > > diff --git a/include/qemu/memfd.h b/include/qemu/memfd.h > index 745a8c501e..41c24d807c 100644 > --- a/include/qemu/memfd.h > +++ b/include/qemu/memfd.h > @@ -16,6 +16,7 @@ > #define F_SEAL_WRITE 0x0008 /* prevent writes */ > #endif > > +int qemu_memfd_create(const char *name, size_t size, unsigned int seals); > void *qemu_memfd_alloc(const char *name, size_t size, unsigned int seals, > int *fd); > void qemu_memfd_free(void *ptr, size_t size, int fd); > diff --git a/util/memfd.c b/util/memfd.c > index 4571d1aba8..e9c1a0e700 100644 > --- a/util/memfd.c > +++ b/util/memfd.c > @@ -55,6 +55,38 @@ static int memfd_create(const char *name, unsigned int flags) > #define MFD_ALLOW_SEALING 0x0002U > #endif > > +int qemu_memfd_create(const char *name, size_t size, unsigned int seals) > +{ > + int mfd = -1; > + > +#ifdef CONFIG_LINUX > + unsigned int flags = MFD_CLOEXEC; > + > + if (seals) { > + flags |= MFD_ALLOW_SEALING; Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> > + } > + > + mfd = memfd_create(name, flags); > + if (mfd < 0) { > + return -1; > + } > + > + if (ftruncate(mfd, size) == -1) { > + perror("ftruncate"); > + close(mfd); > + return -1; > + } > + > + if (seals && fcntl(mfd, F_ADD_SEALS, seals) == -1) { > + perror("fcntl"); > + close(mfd); > + return -1; > + } > +#endif > + > + return mfd; > +} > + > /* > * This is a best-effort helper for shared memory allocation, with > * optional sealing. The helper will do his best to allocate using > @@ -65,35 +97,14 @@ void *qemu_memfd_alloc(const char *name, size_t size, unsigned int seals, > int *fd) > { > void *ptr; > - int mfd = -1; > - > - *fd = -1; > - > -#ifdef CONFIG_LINUX > - if (seals) { > - mfd = memfd_create(name, MFD_ALLOW_SEALING | MFD_CLOEXEC); > - } > + int mfd = qemu_memfd_create(name, size, seals); > > + /* some systems have memfd without sealing */ > if (mfd == -1) { > - /* some systems have memfd without sealing */ > - mfd = memfd_create(name, MFD_CLOEXEC); > - seals = 0; > + mfd = qemu_memfd_create(name, size, 0); > } > -#endif > - > - if (mfd != -1) { > - if (ftruncate(mfd, size) == -1) { > - perror("ftruncate"); > - close(mfd); > - return NULL; > - } > > - if (seals && fcntl(mfd, F_ADD_SEALS, seals) == -1) { > - perror("fcntl"); > - close(mfd); > - return NULL; > - } > - } else { > + if (mfd == -1) { > const char *tmpdir = g_get_tmp_dir(); > gchar *fname; > >
diff --git a/include/qemu/memfd.h b/include/qemu/memfd.h index 745a8c501e..41c24d807c 100644 --- a/include/qemu/memfd.h +++ b/include/qemu/memfd.h @@ -16,6 +16,7 @@ #define F_SEAL_WRITE 0x0008 /* prevent writes */ #endif +int qemu_memfd_create(const char *name, size_t size, unsigned int seals); void *qemu_memfd_alloc(const char *name, size_t size, unsigned int seals, int *fd); void qemu_memfd_free(void *ptr, size_t size, int fd); diff --git a/util/memfd.c b/util/memfd.c index 4571d1aba8..e9c1a0e700 100644 --- a/util/memfd.c +++ b/util/memfd.c @@ -55,6 +55,38 @@ static int memfd_create(const char *name, unsigned int flags) #define MFD_ALLOW_SEALING 0x0002U #endif +int qemu_memfd_create(const char *name, size_t size, unsigned int seals) +{ + int mfd = -1; + +#ifdef CONFIG_LINUX + unsigned int flags = MFD_CLOEXEC; + + if (seals) { + flags |= MFD_ALLOW_SEALING; + } + + mfd = memfd_create(name, flags); + if (mfd < 0) { + return -1; + } + + if (ftruncate(mfd, size) == -1) { + perror("ftruncate"); + close(mfd); + return -1; + } + + if (seals && fcntl(mfd, F_ADD_SEALS, seals) == -1) { + perror("fcntl"); + close(mfd); + return -1; + } +#endif + + return mfd; +} + /* * This is a best-effort helper for shared memory allocation, with * optional sealing. The helper will do his best to allocate using @@ -65,35 +97,14 @@ void *qemu_memfd_alloc(const char *name, size_t size, unsigned int seals, int *fd) { void *ptr; - int mfd = -1; - - *fd = -1; - -#ifdef CONFIG_LINUX - if (seals) { - mfd = memfd_create(name, MFD_ALLOW_SEALING | MFD_CLOEXEC); - } + int mfd = qemu_memfd_create(name, size, seals); + /* some systems have memfd without sealing */ if (mfd == -1) { - /* some systems have memfd without sealing */ - mfd = memfd_create(name, MFD_CLOEXEC); - seals = 0; + mfd = qemu_memfd_create(name, size, 0); } -#endif - - if (mfd != -1) { - if (ftruncate(mfd, size) == -1) { - perror("ftruncate"); - close(mfd); - return NULL; - } - if (seals && fcntl(mfd, F_ADD_SEALS, seals) == -1) { - perror("fcntl"); - close(mfd); - return NULL; - } - } else { + if (mfd == -1) { const char *tmpdir = g_get_tmp_dir(); gchar *fname;
Add a function to only create a memfd, without mmap. The function is used in the following memory backend. Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> --- include/qemu/memfd.h | 1 + util/memfd.c | 61 +++++++++++++++++++++++++++++++--------------------- 2 files changed, 37 insertions(+), 25 deletions(-)