diff options
Diffstat (limited to 'fs/squashfs/super.c')
| -rw-r--r-- | fs/squashfs/super.c | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c index bb44ff4c5cc6..b1b556dbce12 100644 --- 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"); |