From: Alexander Mikhalitsyn <alexander.mikhalit...@virtuozzo.com> This patch adds config OVERLAY_FS_PATH_OPTIONS_MNT_ID compile-time option, and "mnt_id_path_opts" runtime module option. If enabled, user may see mnt_ids for lowerdir, upperdir paths in mountinfo in separate lowerdir_mnt_id/upperdir_mnt_id options.
This patch is very helpful to checkpoint/restore functionality of overlayfs mounts in case when we have overmounts on lowerdir, workdir, upperdir paths. https://jira.sw.ru/browse/PSBM-58614 Signed-off-by: Alexander Mikhalitsyn <alexander.mikhalit...@virtuozzo.com> ===================== Patchset description: overlayfs: C/R enhancements This patchset aimed to make C/R of overlayfs mounts with CRIU possible. We introduce two new overlayfs module options -- dyn_path_opts and mnt_id_path_opts. If enabled this options allows to see real *full* paths in lowerdir, workdir, upperdir options, and also mnt_ids for corresponding paths. This changes should not break anything because for showing mnt_ids we simply introduce new show-time mount options. And for paths we simply *always* provide *full paths* instead of relative path on mountinfo. BEFORE overlay on /var/lib/docker/overlay2/XYZ/merged type overlay (rw,relatime, lowerdir=/var/lib/docker/overlay2/XYZ-init/diff:/var/lib/docker/overlay2/ ABC/diff,upperdir=/var/lib/docker/overlay2/XYZ/diff,workdir=/var/lib/docker /overlay2/XYZ/work) none on /sys type sysfs (rw,relatime) AFTER overlay on /var/lib/docker/overlay2/XYZ/merged type overlay (rw,relatime, lowerdir=/var/lib/docker/overlay2/XYZ-init/diff:/var/lib/docker/overlay2/ ABC/diff,upperdir=/var/lib/docker/overlay2/XYZ/diff,workdir=/var/lib/docker /overlay2/XYZ/work,lowerdir_mnt_id=175:175,upperdir_mnt_id=175) none on /sys type sysfs (rw,relatime) Alexander Mikhalitsyn (2): overlayfs: add dynamic path resolving in mount options overlayfs: add mnt_id paths options ===================== Rebase to RHEL8.3 kernel-4.18.0-240.1.1.el8_3 note: - original patch from vz8 kernel has been dropped (did not apply): c38c281cbe49 ("overlayfs: add mnt_id paths options") - a patchset developed for mainstream has been appliedi (it's not accepted in ms yet): https://lore.kernel.org/lkml/20200604161133.20949-1-alexander.mikhalit...@virtuozzo.com/ +++ fs/overlayfs: Fixed default value for parameter 'mnt_id_path_opts' The value queries .config with IS_ENABLED macro but CONFIG_ prefix is not provided. mFixes: c38c281cbe49 ("overlayfs: add mnt_id paths options") Signed-off-by: Valeriy.Vdovin <valeriy.vdo...@virtuozzo.com> +++ fs/ovelayfs: Fix crash on overlayfs mount Kdump kernel fails to load because of crash on mount of overlayfs: BUG: unable to handle kernel NULL pointer dereference at 0000000000000060 .... Call Trace: seq_path+0x64/0xb0 print_paths_option+0x79/0xa0 ovl_show_options+0x3a/0x320 show_mountinfo+0x1ee/0x290 seq_read+0x2f8/0x400 vfs_read+0x9d/0x150 ksys_read+0x4f/0xb0 do_syscall_64+0x5b/0x1a0 This is cause by OOB access of ofs->lowerpaths. We transfer to print_paths_option() ofs->numlayer as size of ->lowerpaths array, but it's not. The correct number of lowerpaths elements is ->numlower in 'struct ovl_entry'. So move lowerpaths there and use oe->numlower as array size. mFixes: 17fc61697f73 ("overlayfs: add dynamic path resolving in mount options") mFixes: 2191d729083d ("overlayfs: add mnt_id paths options") https://jira.sw.ru/browse/PSBM-123508 Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com> Reviewed-by: Alexander Mikhalitsyn <alexander.mikhalit...@virtuozzo.com> +++ fs/overlayfs: Fix crash on overlayfs mount [ 261.403900] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 [ 261.412847] Call Trace: [ 261.413463] seq_path+0x3c/0xa0 [ 261.414090] print_paths_option+0x8c/0xa0 [ 261.414736] ovl_show_options+0x41/0x320 [ 261.415378] show_mountinfo+0x1df/0x2b0 [ 261.416019] seq_read+0x26e/0x3d0 [ 261.416644] vfs_read+0x89/0x140 [ 261.417269] ksys_read+0x52/0xc0 [ 261.418918] do_syscall_64+0x5b/0x1e0 [ 261.419580] entry_SYSCALL_64_after_hwframe+0x65/0xca [ 261.420256] RIP: 0033:0x7f20b59f28e4 The problem is that we take overlayfs lower layers info not from root dentry. Non-root dentries can have less layers than root dentry. Crash reproducer: mkdir {lower,upper,work,merged} touch lower/lower touch upper/upper touch lowermnt touch uppermnt mount -t overlay overlay -o lowerdir=lower,upperdir=upper,workdir=work merged mount --bind merged/upper uppermnt mount --bind merged/lower lowermnt mFixes: 4267859a0 ("fs/ovelayfs: Fix crash on overlayfs mount") https://jira.sw.ru/browse/PSBM-129333 Signed-off-by: Alexander Mikhalitsyn <alexander.mikhalit...@virtuozzo.com> (cherry picked from vz8 commit d001a4d7b50a13b2f459a307f4542e3beb1ed1fd) Signed-off-by: Andrey Zhadchenko <andrey.zhadche...@virtuozzo.com> --- fs/overlayfs/Kconfig | 26 ++++++++++++++++++++++++++ fs/overlayfs/overlayfs.h | 3 +++ fs/overlayfs/super.c | 15 +++++++++++++++ fs/overlayfs/util.c | 21 +++++++++++++++++++++ 4 files changed, 65 insertions(+) diff --git a/fs/overlayfs/Kconfig b/fs/overlayfs/Kconfig index be733bcd..1ba9411 100644 --- a/fs/overlayfs/Kconfig +++ b/fs/overlayfs/Kconfig @@ -155,3 +155,29 @@ config OVERLAY_FS_DYNAMIC_RESOLVE_PATH_OPTIONS For more information, see Documentation/filesystems/overlayfs.txt If unsure, say N. + +config OVERLAY_FS_PATH_OPTIONS_MNT_ID + bool "Overlayfs: show mnt_id for all mount paths options" + default y + depends on OVERLAY_FS + help + This option helps checkpoint/restore of overlayfs mounts. + If N selected, old behavior is saved. + + If this config option is enabled then in overlay filesystems mount + options you will be able to see additional parameters lowerdir_mnt_id/ + upperdir_mnt_id with corresponding mnt_ids. + + It's also possible to change this behavior on overlayfs module loading or + through sysfs (mnt_id_path_opts parameter). + + Disable this to get a backward compatible with previous kernels configuration, + but in this case checkpoint/restore functionality for overlayfs mounts + may not fully work. + + If backward compatibility is not an issue, then it is safe and + recommended to say Y here. + + For more information, see Documentation/filesystems/overlayfs.txt + + If unsure, say N. diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index d30e097..b4a7d2f 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -355,6 +355,9 @@ static inline bool ovl_test_flag(unsigned long flag, struct inode *inode) void print_path_option(struct seq_file *m, const char *name, struct path *path); void print_paths_option(struct seq_file *m, const char *name, struct path *paths, unsigned int num); +void print_mnt_id_option(struct seq_file *m, const char *name, struct path *path); +void print_mnt_ids_option(struct seq_file *m, const char *name, + struct path *paths, unsigned int num); static inline bool ovl_is_impuredir(struct super_block *sb, struct dentry *dentry) diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index fdb0d9a..065b777 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -57,6 +57,10 @@ module_param_named(dyn_path_opts, ovl_dyn_path_opts, bool, 0644); MODULE_PARM_DESC(dyn_path_opts, "dyn_path_opts feature enabled"); +static bool ovl_mnt_id_path_opts = IS_ENABLED(CONFIG_OVERLAY_FS_PATH_OPTIONS_MNT_ID); +module_param_named(mnt_id_path_opts, ovl_mnt_id_path_opts, bool, 0644); +MODULE_PARM_DESC(mnt_id_path_opts, "mnt_id_path_opts feature enabled"); + static void ovl_entry_stack_free(struct ovl_entry *oe) { unsigned int i; @@ -382,6 +386,17 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry) seq_show_option(m, "workdir", ofs->config.workdir); } } + + if (ovl_mnt_id_path_opts) { + print_mnt_ids_option(m, "lowerdir_mnt_id", oe->lowerpaths, oe->numlower); + /* + * We don't need to show mnt_id for workdir because it + * on the same mount as upperdir. + */ + if (ofs->config.upperdir) + print_mnt_id_option(m, "upperdir_mnt_id", &ofs->upperpath); + } + if (ofs->config.default_permissions) seq_puts(m, ",default_permissions"); if (strcmp(ofs->config.redirect_mode, ovl_redirect_mode_def()) != 0) diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c index 29cf194..0dd8356 100644 --- a/fs/overlayfs/util.c +++ b/fs/overlayfs/util.c @@ -14,6 +14,7 @@ #include <linux/namei.h> #include <linux/ratelimit.h> #include <linux/seq_file.h> +#include "../mount.h" #include "overlayfs.h" int ovl_want_write(struct dentry *dentry) @@ -997,3 +998,23 @@ void print_paths_option(struct seq_file *m, const char *name, seq_path(m, &paths[i], ", \t\n\\"); } } + +void print_mnt_id_option(struct seq_file *m, const char *name, struct path *path) +{ + seq_show_option(m, name, ""); + seq_printf(m, "%i", real_mount(path->mnt)->mnt_id); +} + +void print_mnt_ids_option(struct seq_file *m, const char *name, + struct path *paths, unsigned int num) +{ + int i; + + seq_show_option(m, name, ""); + + for (i = 0; i < num; i++) { + if (i) + seq_putc(m, ':'); + seq_printf(m, "%i", real_mount(paths[i].mnt)->mnt_id); + } +} -- 1.8.3.1 _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel
