X-Git-Url: https://git.karo-electronics.de/?a=blobdiff_plain;f=mm%2Fshmem.c;h=8f419cff9e3451fa3b4a98026d332d45ae80ea86;hb=f736d9985e69e72d9a2ebfd131a72ee8f870c6f3;hp=5402481c28d190a83718f6b1897eec78df4c0209;hpb=c5aec4c76af1a2d89ee2f2d4d5463b2ad2d85de5;p=karo-tx-linux.git diff --git a/mm/shmem.c b/mm/shmem.c index 5402481c28d1..8f419cff9e34 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -80,11 +80,12 @@ static struct vfsmount *shm_mnt; #define SHORT_SYMLINK_LEN 128 /* - * shmem_fallocate and shmem_writepage communicate via inode->i_private - * (with i_mutex making sure that it has only one user at a time): - * we would prefer not to enlarge the shmem inode just for that. + * shmem_fallocate communicates with shmem_fault or shmem_writepage via + * inode->i_private (with i_mutex making sure that it has only one user at + * a time): we would prefer not to enlarge the shmem inode just for that. */ struct shmem_falloc { + int mode; /* FALLOC_FL mode currently operating */ pgoff_t start; /* start of range currently being fallocated */ pgoff_t next; /* the next page offset to be fallocated */ pgoff_t nr_falloced; /* how many new pages have been fallocated */ @@ -759,6 +760,7 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) spin_lock(&inode->i_lock); shmem_falloc = inode->i_private; if (shmem_falloc && + !shmem_falloc->mode && index >= shmem_falloc->start && index < shmem_falloc->next) shmem_falloc->nr_unswapped++; @@ -1233,6 +1235,44 @@ static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) int error; int ret = VM_FAULT_LOCKED; + /* + * Trinity finds that probing a hole which tmpfs is punching can + * prevent the hole-punch from ever completing: which in turn + * locks writers out with its hold on i_mutex. So refrain from + * faulting pages into the hole while it's being punched, and + * wait on i_mutex to be released if vmf->flags permits. + */ + if (unlikely(inode->i_private)) { + struct shmem_falloc *shmem_falloc; + + spin_lock(&inode->i_lock); + shmem_falloc = inode->i_private; + if (!shmem_falloc || + shmem_falloc->mode != FALLOC_FL_PUNCH_HOLE || + vmf->pgoff < shmem_falloc->start || + vmf->pgoff >= shmem_falloc->next) + shmem_falloc = NULL; + spin_unlock(&inode->i_lock); + /* + * i_lock has protected us from taking shmem_falloc seriously + * once return from shmem_fallocate() went back up that stack. + * i_lock does not serialize with i_mutex at all, but it does + * not matter if sometimes we wait unnecessarily, or sometimes + * miss out on waiting: we just need to make those cases rare. + */ + if (shmem_falloc) { + if ((vmf->flags & FAULT_FLAG_ALLOW_RETRY) && + !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) { + up_read(&vma->vm_mm->mmap_sem); + mutex_lock(&inode->i_mutex); + mutex_unlock(&inode->i_mutex); + return VM_FAULT_RETRY; + } + /* cond_resched? Leave that to GUP or return to user */ + return VM_FAULT_NOPAGE; + } + } + error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); if (error) return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); @@ -1406,8 +1446,7 @@ shmem_write_end(struct file *file, struct address_space *mapping, return copied; } -static ssize_t shmem_file_aio_read(struct kiocb *iocb, - const struct iovec *iov, unsigned long nr_segs, loff_t pos) +static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to) { struct file *file = iocb->ki_filp; struct inode *inode = file_inode(file); @@ -1416,15 +1455,8 @@ static ssize_t shmem_file_aio_read(struct kiocb *iocb, unsigned long offset; enum sgp_type sgp = SGP_READ; int error = 0; - ssize_t retval; - size_t count; + ssize_t retval = 0; loff_t *ppos = &iocb->ki_pos; - struct iov_iter iter; - - retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); - if (retval) - return retval; - iov_iter_init(&iter, iov, nr_segs, count, 0); /* * Might this read be for a stacking filesystem? Then when reading @@ -1500,14 +1532,14 @@ static ssize_t shmem_file_aio_read(struct kiocb *iocb, * Ok, we have the page, and it's up-to-date, so * now we can copy it to user space... */ - ret = copy_page_to_iter(page, offset, nr, &iter); + ret = copy_page_to_iter(page, offset, nr, to); retval += ret; offset += ret; index += offset >> PAGE_CACHE_SHIFT; offset &= ~PAGE_CACHE_MASK; page_cache_release(page); - if (!iov_iter_count(&iter)) + if (!iov_iter_count(to)) break; if (ret < nr) { error = -EFAULT; @@ -1732,20 +1764,31 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset, pgoff_t start, index, end; int error; + if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE)) + return -EOPNOTSUPP; + mutex_lock(&inode->i_mutex); + shmem_falloc.mode = mode & ~FALLOC_FL_KEEP_SIZE; + if (mode & FALLOC_FL_PUNCH_HOLE) { struct address_space *mapping = file->f_mapping; loff_t unmap_start = round_up(offset, PAGE_SIZE); loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1; + shmem_falloc.start = unmap_start >> PAGE_SHIFT; + shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT; + spin_lock(&inode->i_lock); + inode->i_private = &shmem_falloc; + spin_unlock(&inode->i_lock); + if ((u64)unmap_end > (u64)unmap_start) unmap_mapping_range(mapping, unmap_start, 1 + unmap_end - unmap_start, 0); shmem_truncate_range(inode, offset, offset + len - 1); /* No need to unmap again: hole-punching leaves COWed pages */ error = 0; - goto out; + goto undone; } /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */ @@ -2629,13 +2672,13 @@ static const struct file_operations shmem_file_operations = { .mmap = shmem_mmap, #ifdef CONFIG_TMPFS .llseek = shmem_file_llseek, - .read = do_sync_read, - .write = do_sync_write, - .aio_read = shmem_file_aio_read, - .aio_write = generic_file_aio_write, + .read = new_sync_read, + .write = new_sync_write, + .read_iter = shmem_file_read_iter, + .write_iter = generic_file_write_iter, .fsync = noop_fsync, .splice_read = shmem_file_splice_read, - .splice_write = generic_file_splice_write, + .splice_write = iter_file_splice_write, .fallocate = shmem_fallocate, #endif };