Merge tag 'arc-5.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc

[linux-2.6-microblaze.git] / fs / squashfs / super.c

diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c
index bb44ff4..b1b556d 100644 (file)
--- a/fs/squashfs/super.c
+++ b/fs/squashfs/super.c
@@ -29,6 +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"
@@ -112,6 +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)
 {
@@ -127,6 +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");