Commit 53afcd31 authored by Amir Goldstein's avatar Amir Goldstein Committed by Miklos Szeredi
Browse files

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: 0f831ec8 ("ovl: simplify ovl_same_sb() helper")
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 531d3040

fs/overlayfs/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -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

fs/overlayfs/super.c

+8 −1
Original line number Diff line number Diff line
@@ -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;

	} 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
@@ -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 */

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

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

		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;

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