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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: 0f831ec85e ("ovl: simplify ovl_same_sb() helper")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Amir Goldstein 2020-02-21 16:34:42 +02:00 committed by Miklos Szeredi
parent 531d3040bc
commit 53afcd310e
2 changed files with 9 additions and 1 deletions
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1
fs/overlayfs/Kconfig
View File

@ -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

9
fs/overlayfs/super.c
View File

@ -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;