buffer: calculate block number inside folio_init_buffers()

The calculation of block from index doesn't work for devices with a block
size larger than PAGE_SIZE as we end up shifting by a negative number.
Instead, calculate the number of the first block from the folio's position
in the block device.  We no longer need to pass sizebits to
grow_dev_folio().

Link: https://lkml.kernel.org/r/20231109210608.2252323-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Pankaj Raghav <p.raghav@samsung.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/buffer.c b/fs/buffer.c
index 8dad6c691e143a8401cf1fdd432f8559f62d4d91..44e0c0b7f71f487019395c50331a7bd852a6c87f 100644 (file)
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -995,11 +995,12 @@ static sector_t blkdev_max_block(struct block_device *bdev, unsigned int size)
  * Initialise the state of a blockdev folio's buffers.
  */ 
 static sector_t folio_init_buffers(struct folio *folio,
-               struct block_device *bdev, sector_t block, int size)
+               struct block_device *bdev, unsigned size)
 {
        struct buffer_head *head = folio_buffers(folio);
        struct buffer_head *bh = head;
        bool uptodate = folio_test_uptodate(folio);
+       sector_t block = div_u64(folio_pos(folio), size);
        sector_t end_block = blkdev_max_block(bdev, size);
 
        do {
@@ -1032,7 +1033,7 @@ static sector_t folio_init_buffers(struct folio *folio,
  * we succeeded, or the caller should retry.
  */
 static bool grow_dev_folio(struct block_device *bdev, sector_t block,
-               pgoff_t index, unsigned size, int sizebits, gfp_t gfp)
+               pgoff_t index, unsigned size, gfp_t gfp)
 {
        struct inode *inode = bdev->bd_inode;
        struct folio *folio;
@@ -1047,8 +1048,7 @@ static bool grow_dev_folio(struct block_device *bdev, sector_t block,
        bh = folio_buffers(folio);
        if (bh) {
                if (bh->b_size == size) {
-                       end_block = folio_init_buffers(folio, bdev,
-                                       (sector_t)index << sizebits, size);
+                       end_block = folio_init_buffers(folio, bdev, size);
                        goto unlock;
                }
 
@@ -1069,8 +1069,7 @@ static bool grow_dev_folio(struct block_device *bdev, sector_t block,
         */
        spin_lock(&inode->i_mapping->private_lock);
        link_dev_buffers(folio, bh);
-       end_block = folio_init_buffers(folio, bdev,
-                       (sector_t)index << sizebits, size);
+       end_block = folio_init_buffers(folio, bdev, size);
        spin_unlock(&inode->i_mapping->private_lock);
 unlock:
        folio_unlock(folio);
@@ -1105,7 +1104,7 @@ static bool grow_buffers(struct block_device *bdev, sector_t block,
        }
 
        /* Create a folio with the proper size buffers */
-       return grow_dev_folio(bdev, block, index, size, sizebits, gfp);
+       return grow_dev_folio(bdev, block, index, size, gfp);
 }
 
 static struct buffer_head *