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-rw-r--r--mm/shmem.c61
1 files changed, 60 insertions, 1 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index f368d0acb52..9b90d89e54c 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1602,7 +1602,9 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset,
loff_t len)
{
struct inode *inode = file->f_path.dentry->d_inode;
- int error = -EOPNOTSUPP;
+ struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
+ pgoff_t start, index, end;
+ int error;
mutex_lock(&inode->i_mutex);
@@ -1617,8 +1619,65 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset,
shmem_truncate_range(inode, offset, offset + len - 1);
/* No need to unmap again: hole-punching leaves COWed pages */
error = 0;
+ goto out;
}
+ /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
+ error = inode_newsize_ok(inode, offset + len);
+ if (error)
+ goto out;
+
+ start = offset >> PAGE_CACHE_SHIFT;
+ end = (offset + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+ /* Try to avoid a swapstorm if len is impossible to satisfy */
+ if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) {
+ error = -ENOSPC;
+ goto out;
+ }
+
+ for (index = start; index < end; index++) {
+ struct page *page;
+
+ /*
+ * Good, the fallocate(2) manpage permits EINTR: we may have
+ * been interrupted because we are using up too much memory.
+ */
+ if (signal_pending(current))
+ error = -EINTR;
+ else
+ error = shmem_getpage(inode, index, &page, SGP_WRITE,
+ NULL);
+ if (error) {
+ /*
+ * We really ought to free what we allocated so far,
+ * but it would be wrong to free pages allocated
+ * earlier, or already now in use: i_mutex does not
+ * exclude all cases. We do not know what to free.
+ */
+ goto ctime;
+ }
+
+ if (!PageUptodate(page)) {
+ clear_highpage(page);
+ flush_dcache_page(page);
+ SetPageUptodate(page);
+ }
+ /*
+ * set_page_dirty so that memory pressure will swap rather
+ * than free the pages we are allocating (and SGP_CACHE pages
+ * might still be clean: we now need to mark those dirty too).
+ */
+ set_page_dirty(page);
+ unlock_page(page);
+ page_cache_release(page);
+ cond_resched();
+ }
+
+ if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
+ i_size_write(inode, offset + len);
+ctime:
+ inode->i_ctime = CURRENT_TIME;
+out:
mutex_unlock(&inode->i_mutex);
return error;
}