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| author | Will Deacon <will.deacon@arm.com> | 2012-06-07 14:21:13 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-06-07 14:43:55 -0700 |
| commit | 7d8a45695cc8f9fcdf4121fcbd897ecb63f758e4 (patch) | |
| tree | ba315d40c8b0457d132ea155d0db651275af6822 /ipc/shm.c | |
| parent | 4e791c98ae7ff889121ca93b7bd97206e4a8d793 (diff) | |
| download | lwn-7d8a45695cc8f9fcdf4121fcbd897ecb63f758e4.tar.gz lwn-7d8a45695cc8f9fcdf4121fcbd897ecb63f758e4.zip | |
ipc: shm: restore MADV_REMOVE functionality on shared memory segments
Commit 17cf28afea2a ("mm/fs: remove truncate_range") removed the
truncate_range inode operation in favour of the fallocate file
operation.
When using SYSV IPC shared memory segments, calling madvise with the
MADV_REMOVE advice on an area of shared memory will attempt to invoke
the .fallocate function for the shm_file_operations, which is NULL and
therefore returns -EOPNOTSUPP to userspace. The previous behaviour
would inherit the inode_operations from the underlying tmpfs file and
invoke truncate_range there.
This patch restores the previous behaviour by wrapping the underlying
fallocate function in shm_fallocate, as we do for fsync.
[hughd@google.com: use -ENOTSUPP in shm_fallocate()]
Signed-off-by: Will Deacon <will.deacon@arm.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc/shm.c')
| -rw-r--r-- | ipc/shm.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/ipc/shm.c b/ipc/shm.c index 5e2cbfdab6fc..41c1285d697a 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -393,6 +393,16 @@ static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync) return sfd->file->f_op->fsync(sfd->file, start, end, datasync); } +static long shm_fallocate(struct file *file, int mode, loff_t offset, + loff_t len) +{ + struct shm_file_data *sfd = shm_file_data(file); + + if (!sfd->file->f_op->fallocate) + return -EOPNOTSUPP; + return sfd->file->f_op->fallocate(file, mode, offset, len); +} + static unsigned long shm_get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags) @@ -410,6 +420,7 @@ static const struct file_operations shm_file_operations = { .get_unmapped_area = shm_get_unmapped_area, #endif .llseek = noop_llseek, + .fallocate = shm_fallocate, }; static const struct file_operations shm_file_operations_huge = { @@ -418,6 +429,7 @@ static const struct file_operations shm_file_operations_huge = { .release = shm_release, .get_unmapped_area = shm_get_unmapped_area, .llseek = noop_llseek, + .fallocate = shm_fallocate, }; int is_file_shm_hugepages(struct file *file) |