ovl: fix some xino configurations

Fix up two bugs in the coversion to xino_mode:
1. xino=off does not always end up in disabled mode
2. xino=auto on 32bit arch should end up in disabled mode

Take a proactive approach to disabling xino on 32bit kernel:
1. Disable XINO_AUTO config during build time
2. Disable xino with a warning on mount time

As a by product, xino=on on 32bit arch also ends up in disabled mode.
We never intended to enable xino on 32bit arch and this will make the
rest of the logic simpler.

Fixes: 0f831ec85eda ("ovl: simplify ovl_same_sb() helper")
Signed-off-by: Amir Goldstein <[email protected]>
Signed-off-by: Miklos Szeredi <[email protected]>

diff --git a/fs/overlayfs/Kconfig b/fs/overlayfs/Kconfig
index 444e2da4f60e213c28109204fdd997dab4b863a3..714c14c47ca5573053b43fb605c69761d2157562 100644 (file)
--- a/fs/overlayfs/Kconfig
+++ b/fs/overlayfs/Kconfig
@@ -93,6 +93,7 @@ config OVERLAY_FS_XINO_AUTO
        bool "Overlayfs: auto enable inode number mapping"
        default n
        depends on OVERLAY_FS
        bool "Overlayfs: auto enable inode number mapping"
        default n
        depends on OVERLAY_FS

+       depends on 64BIT

        help
          If this config option is enabled then overlay filesystems will use
          unused high bits in undelying filesystem inode numbers to map all
        help
          If this config option is enabled then overlay filesystems will use
          unused high bits in undelying filesystem inode numbers to map all

diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 319fe0d355b0b33b5cda8f3227f17a09e8de7049..ac967f1cb6e505725515863395d273122e013129 100644 (file)
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -1411,6 +1411,8 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
                if (ofs->config.xino == OVL_XINO_ON)
                        pr_info("\"xino=on\" is useless with all layers on same fs, ignore.\n");
                ofs->xino_mode = 0;
                if (ofs->config.xino == OVL_XINO_ON)
                        pr_info("\"xino=on\" is useless with all layers on same fs, ignore.\n");
                ofs->xino_mode = 0;

+       } else if (ofs->config.xino == OVL_XINO_OFF) {
+               ofs->xino_mode = -1;

        } else if (ofs->config.xino == OVL_XINO_ON && ofs->xino_mode < 0) {
                /*
                 * This is a roundup of number of bits needed for encoding
        } else if (ofs->config.xino == OVL_XINO_ON && ofs->xino_mode < 0) {
                /*
                 * This is a roundup of number of bits needed for encoding


@@ -1623,8 +1625,13 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
        sb->s_stack_depth = 0;
        sb->s_maxbytes = MAX_LFS_FILESIZE;
        /* Assume underlaying fs uses 32bit inodes unless proven otherwise */
        sb->s_stack_depth = 0;
        sb->s_maxbytes = MAX_LFS_FILESIZE;
        /* Assume underlaying fs uses 32bit inodes unless proven otherwise */

-       if (ofs->config.xino != OVL_XINO_OFF)
+       if (ofs->config.xino != OVL_XINO_OFF) {

                ofs->xino_mode = BITS_PER_LONG - 32;
                ofs->xino_mode = BITS_PER_LONG - 32;

+               if (!ofs->xino_mode) {
+                       pr_warn("xino not supported on 32bit kernel, falling back to xino=off.\n");
+                       ofs->config.xino = OVL_XINO_OFF;
+               }
+       }

 
        /* alloc/destroy_inode needed for setting up traps in inode cache */
        sb->s_op = &ovl_super_operations;
 
        /* alloc/destroy_inode needed for setting up traps in inode cache */
        sb->s_op = &ovl_super_operations;