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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>

Will Deacon committed 14 years ago

Commit 7d8a4561 parent 4e791c91 file · +12 −0Browse files

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ipc/shm.c+12−0
@@ -393,6 +393,16 @@ static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync) · 392 unmodified lines
393 return sfd->file->f_op->fsync(sfd->file, start, end, datasync);393 return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
394}394}
395 395
396static long shm_fallocate(struct file *file, int mode, loff_t offset,
397 loff_t len)
398{
399 struct shm_file_data *sfd = shm_file_data(file);
400
401 if (!sfd->file->f_op->fallocate)
402 return -EOPNOTSUPP;
403 return sfd->file->f_op->fallocate(file, mode, offset, len);
404}
405
396static unsigned long shm_get_unmapped_area(struct file *file,406static unsigned long shm_get_unmapped_area(struct file *file,
397 unsigned long addr, unsigned long len, unsigned long pgoff,407 unsigned long addr, unsigned long len, unsigned long pgoff,
398 unsigned long flags)408 unsigned long flags)
@@ -410,6 +420,7 @@ static const struct file_operations shm_file_operations = { · 11 unmodified lines
410 .get_unmapped_area = shm_get_unmapped_area,420 .get_unmapped_area = shm_get_unmapped_area,
411#endif421#endif
412 .llseek = noop_llseek,422 .llseek = noop_llseek,
423 .fallocate = shm_fallocate,
413};424};
414 425
415static const struct file_operations shm_file_operations_huge = {426static const struct file_operations shm_file_operations_huge = {
@@ -418,6 +429,7 @@ static const struct file_operations shm_file_operations_huge = { · 2 unmodified lines
418 .release = shm_release,429 .release = shm_release,
419 .get_unmapped_area = shm_get_unmapped_area,430 .get_unmapped_area = shm_get_unmapped_area,
420 .llseek = noop_llseek,431 .llseek = noop_llseek,
432 .fallocate = shm_fallocate,
421};433};
422 434
423int is_file_shm_hugepages(struct file *file)435int is_file_shm_hugepages(struct file *file)