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>
Unified · Split
| @@ -393,6 +393,16 @@ static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync) · 392 unmodified lines | ||
| 393 | 393 | return sfd->file->f_op->fsync(sfd->file, start, end, datasync); |
| 394 | 394 | } |
| 395 | 395 | |
| 396 | +static 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 | + | |
| 396 | 406 | static unsigned long shm_get_unmapped_area(struct file *file, |
| 397 | 407 | unsigned long addr, unsigned long len, unsigned long pgoff, |
| 398 | 408 | unsigned long flags) |
| @@ -410,6 +420,7 @@ static const struct file_operations shm_file_operations = { · 11 unmodified lines | ||
| 410 | 420 | .get_unmapped_area = shm_get_unmapped_area, |
| 411 | 421 | #endif |
| 412 | 422 | .llseek = noop_llseek, |
| 423 | + .fallocate = shm_fallocate, | |
| 413 | 424 | }; |
| 414 | 425 | |
| 415 | 426 | static 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 | 429 | .release = shm_release, |
| 419 | 430 | .get_unmapped_area = shm_get_unmapped_area, |
| 420 | 431 | .llseek = noop_llseek, |
| 432 | + .fallocate = shm_fallocate, | |
| 421 | 433 | }; |
| 422 | 434 | |
| 423 | 435 | int is_file_shm_hugepages(struct file *file) |