Merge tag 'iomap-5.5-merge-14' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux

Pull iomap fixes from Darrick Wong:
 "Fix a race condition and a use-after-free error:

   - Fix a UAF when reporting writeback errors

   - Fix a race condition when handling page uptodate on fragmented file
     with blocksize < pagesize"

* tag 'iomap-5.5-merge-14' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  iomap: stop using ioend after it's been freed in iomap_finish_ioend()
  iomap: fix sub-page uptodate handling

Author: torvalds

fs/iomap/buffered-io.c

@@ -28,6 +28,7 @@
 struct iomap_page {
 	atomic_t		read_count;
 	atomic_t		write_count;
+	spinlock_t		uptodate_lock;
 	DECLARE_BITMAP(uptodate, PAGE_SIZE / 512);
 };
 
@@ -51,6 +52,7 @@ iomap_page_create(struct inode *inode, struct page *page)
 	iop = kmalloc(sizeof(*iop), GFP_NOFS | __GFP_NOFAIL);
 	atomic_set(&iop->read_count, 0);
 	atomic_set(&iop->write_count, 0);
+	spin_lock_init(&iop->uptodate_lock);
 	bitmap_zero(iop->uptodate, PAGE_SIZE / SECTOR_SIZE);
 
 	/*
@@ -139,25 +141,38 @@ iomap_adjust_read_range(struct inode *inode, struct iomap_page *iop,
 }
 
 static void
-iomap_set_range_uptodate(struct page *page, unsigned off, unsigned len)
+iomap_iop_set_range_uptodate(struct page *page, unsigned off, unsigned len)
 {
 	struct iomap_page *iop = to_iomap_page(page);
 	struct inode *inode = page->mapping->host;
 	unsigned first = off >> inode->i_blkbits;
 	unsigned last = (off + len - 1) >> inode->i_blkbits;
-	unsigned int i;
 	bool uptodate = true;
+	unsigned long flags;
+	unsigned int i;
 
-	if (iop) {
-		for (i = 0; i < PAGE_SIZE / i_blocksize(inode); i++) {
-			if (i >= first && i <= last)
-				set_bit(i, iop->uptodate);
-			else if (!test_bit(i, iop->uptodate))
-				uptodate = false;
-		}
+	spin_lock_irqsave(&iop->uptodate_lock, flags);
+	for (i = 0; i < PAGE_SIZE / i_blocksize(inode); i++) {
+		if (i >= first && i <= last)
+			set_bit(i, iop->uptodate);
+		else if (!test_bit(i, iop->uptodate))
+			uptodate = false;
 	}
 
-	if (uptodate && !PageError(page))
+	if (uptodate)
+		SetPageUptodate(page);
+	spin_unlock_irqrestore(&iop->uptodate_lock, flags);
+}
+
+static void
+iomap_set_range_uptodate(struct page *page, unsigned off, unsigned len)
+{
+	if (PageError(page))
+		return;
+
+	if (page_has_private(page))
+		iomap_iop_set_range_uptodate(page, off, len);
+	else
 		SetPageUptodate(page);
 }
 
@@ -1128,6 +1143,7 @@ iomap_finish_ioend(struct iomap_ioend *ioend, int error)
 	struct bio *bio = &ioend->io_inline_bio;
 	struct bio *last = ioend->io_bio, *next;
 	u64 start = bio->bi_iter.bi_sector;
+	loff_t offset = ioend->io_offset;
 	bool quiet = bio_flagged(bio, BIO_QUIET);
 
 	for (bio = &ioend->io_inline_bio; bio; bio = next) {
@@ -1148,12 +1164,12 @@ iomap_finish_ioend(struct iomap_ioend *ioend, int error)
 			iomap_finish_page_writeback(inode, bv->bv_page, error);
 		bio_put(bio);
 	}
+	/* The ioend has been freed by bio_put() */
 
 	if (unlikely(error && !quiet)) {
 		printk_ratelimited(KERN_ERR
 "%s: writeback error on inode %lu, offset %lld, sector %llu",
-			inode->i_sb->s_id, inode->i_ino, ioend->io_offset,
-			start);
+			inode->i_sb->s_id, inode->i_ino, offset, start);
 	}
 }