Fix up two bugs in the coversion to xino_mode:
1. xino=off does not alway 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 <amir73il@xxxxxxxxx>
---
fs/overlayfs/Kconfig | 1 +
fs/overlayfs/super.c | 9 ++++++++-
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/fs/overlayfs/Kconfig b/fs/overlayfs/Kconfig
index 444e2da4f60e..714c14c47ca5 100644
--- 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
+ 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
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 6dc45bc7d664..f4c0ad69f9a6 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -1489,6 +1489,8 @@ 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;
+ } 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
@@ -1735,8 +1737,13 @@ 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 */
- if (ofs->config.xino != OVL_XINO_OFF)
+ if (ofs->config.xino != OVL_XINO_OFF) {
ofs->xino_mode = BITS_PER_LONG - 32;
+ if (!ofs->config.xino) {
+ 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;
--
2.17.1
