1 files changed, 37 insertions, 3 deletions

diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c
index 60d6951915f4..4f74abbc1a54 100644
--- a/fs/squashfs/super.c
+++ b/fs/squashfs/super.c
@@ -16,6 +16,7 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/blkdev.h>
 #include <linux/fs.h>
 #include <linux/fs_context.h>
 #include <linux/fs_parser.h>
@@ -28,6 +29,7 @@
 #include <linux/module.h>
 #include <linux/magic.h>
 #include <linux/xattr.h>
+#include <linux/backing-dev.h>
 
 #include "squashfs_fs.h"
 #include "squashfs_fs_sb.h"
@@ -111,6 +113,24 @@ static const struct squashfs_decompressor *supported_squashfs_filesystem(
 	return decompressor;
 }
 
+static int squashfs_bdi_init(struct super_block *sb)
+{
+	int err;
+	unsigned int major = MAJOR(sb->s_dev);
+	unsigned int minor = MINOR(sb->s_dev);
+
+	bdi_put(sb->s_bdi);
+	sb->s_bdi = &noop_backing_dev_info;
+
+	err = super_setup_bdi_name(sb, "squashfs_%u_%u", major, minor);
+	if (err)
+		return err;
+
+	sb->s_bdi->ra_pages = 0;
+	sb->s_bdi->io_pages = 0;
+
+	return 0;
+}
 
 static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
 {
@@ -126,6 +146,20 @@ static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
 
 	TRACE("Entered squashfs_fill_superblock\n");
 
+	/*
+	 * squashfs provides 'backing_dev_info' in order to disable read-ahead. For
+	 * squashfs, I/O is not deferred, it is done immediately in readpage,
+	 * which means the user would always have to wait their own I/O. So the effect
+	 * of readahead is very weak for squashfs. squashfs_bdi_init will set
+	 * sb->s_bdi->ra_pages and sb->s_bdi->io_pages to 0 and close readahead for
+	 * squashfs.
+	 */
+	err = squashfs_bdi_init(sb);
+	if (err) {
+		errorf(fc, "squashfs init bdi failed");
+		return err;
+	}
+
 	sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
 	if (sb->s_fs_info == NULL) {
 		ERROR("Failed to allocate squashfs_sb_info\n");
@@ -179,8 +213,8 @@ static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
 	/* Check the filesystem does not extend beyond the end of the
 	   block device */
 	msblk->bytes_used = le64_to_cpu(sblk->bytes_used);
-	if (msblk->bytes_used < 0 || msblk->bytes_used >
-			i_size_read(sb->s_bdev->bd_inode))
+	if (msblk->bytes_used < 0 ||
+	    msblk->bytes_used > bdev_nr_bytes(sb->s_bdev))
 		goto failed_mount;
 
 	/* Check block size for sanity */
@@ -550,7 +584,7 @@ static void __exit exit_squashfs_fs(void)
 static struct inode *squashfs_alloc_inode(struct super_block *sb)
 {
 	struct squashfs_inode_info *ei =
-		kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL);
+		alloc_inode_sb(sb, squashfs_inode_cachep, GFP_KERNEL);
 
 	return ei ? &ei->vfs_inode : NULL;
 }