target: Fix bug in handling of FILEIO + block_device resize ops

This patch fixes a bug in the handling of FILEIO w/ underlying block_device
resize operations where the original fd_dev->fd_dev_size was incorrectly being
used in fd_get_blocks() for READ_CAPACITY response payloads.

This patch avoids using fd_dev->fd_dev_size for FILEIO devices with
an underlying block_device, and instead changes fd_get_blocks() to
get the sector count directly from i_size_read() as recommended by hch.

Reported-by: Christoph Hellwig <hch@lst.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c
index 7ed58e2..f286955 100644 (file)
--- a/drivers/target/target_core_file.c
+++ b/drivers/target/target_core_file.c
@@ -169,6 +169,7 @@ static struct se_device *fd_create_virtdevice(
        inode = file->f_mapping->host;
        if (S_ISBLK(inode->i_mode)) {
                struct request_queue *q;
+               unsigned long long dev_size;
                /*
                 * Setup the local scope queue_limits from struct request_queue->limits
                 * to pass into transport_add_device_to_core_hba() as struct se_dev_limits.
@@ -183,13 +184,12 @@ static struct se_device *fd_create_virtdevice(
                 * one (1) logical sector from underlying struct block_device
                 */
                fd_dev->fd_block_size = bdev_logical_block_size(inode->i_bdev);
-               fd_dev->fd_dev_size = (i_size_read(file->f_mapping->host) -
+               dev_size = (i_size_read(file->f_mapping->host) -
                                       fd_dev->fd_block_size);
 
                pr_debug("FILEIO: Using size: %llu bytes from struct"
                        " block_device blocks: %llu logical_block_size: %d\n",
-                       fd_dev->fd_dev_size,
-                       div_u64(fd_dev->fd_dev_size, fd_dev->fd_block_size),
+                       dev_size, div_u64(dev_size, fd_dev->fd_block_size),
                        fd_dev->fd_block_size);
        } else {
                if (!(fd_dev->fbd_flags & FBDF_HAS_SIZE)) {
@@ -605,10 +605,20 @@ static u32 fd_get_device_type(struct se_device *dev)
 static sector_t fd_get_blocks(struct se_device *dev)
 {
        struct fd_dev *fd_dev = dev->dev_ptr;
-       unsigned long long blocks_long = div_u64(fd_dev->fd_dev_size,
-                       dev->se_sub_dev->se_dev_attrib.block_size);
+       struct file *f = fd_dev->fd_file;
+       struct inode *i = f->f_mapping->host;
+       unsigned long long dev_size;
+       /*
+        * When using a file that references an underlying struct block_device,
+        * ensure dev_size is always based on the current inode size in order
+        * to handle underlying block_device resize operations.
+        */
+       if (S_ISBLK(i->i_mode))
+               dev_size = (i_size_read(i) - fd_dev->fd_block_size);
+       else
+               dev_size = fd_dev->fd_dev_size;
 
-       return blocks_long;
+       return div_u64(dev_size, dev->se_sub_dev->se_dev_attrib.block_size);
 }
 
 static struct se_subsystem_api fileio_template = {