diff options
| -rw-r--r-- | fs/overlayfs/Kconfig | 20 | ||||
| -rw-r--r-- | fs/overlayfs/copy_up.c | 9 | ||||
| -rw-r--r-- | fs/overlayfs/overlayfs.h | 2 | ||||
| -rw-r--r-- | fs/overlayfs/ovl_entry.h | 3 | ||||
| -rw-r--r-- | fs/overlayfs/super.c | 66 | ||||
| -rw-r--r-- | fs/overlayfs/util.c | 15 |
6 files changed, 108 insertions, 7 deletions
diff --git a/fs/overlayfs/Kconfig b/fs/overlayfs/Kconfig index c0c9683934b7..cbfc196e5dc5 100644 --- a/fs/overlayfs/Kconfig +++ b/fs/overlayfs/Kconfig @@ -23,3 +23,23 @@ config OVERLAY_FS_REDIRECT_DIR Note, that redirects are not backward compatible. That is, mounting an overlay which has redirects on a kernel that doesn't support this feature will have unexpected results. + +config OVERLAY_FS_INDEX + bool "Overlayfs: turn on inodes index feature by default" + depends on OVERLAY_FS + help + If this config option is enabled then overlay filesystems will use + the inodes index dir to map lower inodes to upper inodes by default. + In this case it is still possible to turn off index globally with the + "index=off" module option or on a filesystem instance basis with the + "index=off" mount option. + + The inodes index feature prevents breaking of lower hardlinks on copy + up. + + Note, that the inodes index feature is read-only backward compatible. + That is, mounting an overlay which has an index dir on a kernel that + doesn't support this feature read-only, will not have any negative + outcomes. However, mounting the same overlay with an old kernel + read-write and then mounting it again with a new kernel, will have + unexpected results. diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index 87289b9a152c..f9f51cce3c18 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -233,12 +233,13 @@ int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat) return err; } -static struct ovl_fh *ovl_encode_fh(struct dentry *lower, uuid_t *uuid) +static struct ovl_fh *ovl_encode_fh(struct dentry *lower) { struct ovl_fh *fh; int fh_type, fh_len, dwords; void *buf; int buflen = MAX_HANDLE_SZ; + uuid_t *uuid = &lower->d_sb->s_uuid; buf = kmalloc(buflen, GFP_TEMPORARY); if (!buf) @@ -283,7 +284,6 @@ out: static int ovl_set_origin(struct dentry *dentry, struct dentry *lower, struct dentry *upper) { - struct super_block *sb = lower->d_sb; const struct ovl_fh *fh = NULL; int err; @@ -292,9 +292,8 @@ static int ovl_set_origin(struct dentry *dentry, struct dentry *lower, * so we can use the overlay.origin xattr to distignuish between a copy * up and a pure upper inode. */ - if (sb->s_export_op && sb->s_export_op->fh_to_dentry && - !uuid_is_null(&sb->s_uuid)) { - fh = ovl_encode_fh(lower, &sb->s_uuid); + if (ovl_can_decode_fh(lower->d_sb)) { + fh = ovl_encode_fh(lower); if (IS_ERR(fh)) return PTR_ERR(fh); } diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index 5e958427463d..4e7a74e99d3c 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -183,6 +183,8 @@ void ovl_drop_write(struct dentry *dentry); struct dentry *ovl_workdir(struct dentry *dentry); const struct cred *ovl_override_creds(struct super_block *sb); struct super_block *ovl_same_sb(struct super_block *sb); +bool ovl_can_decode_fh(struct super_block *sb); +struct dentry *ovl_indexdir(struct super_block *sb); struct ovl_entry *ovl_alloc_entry(unsigned int numlower); bool ovl_dentry_remote(struct dentry *dentry); bool ovl_dentry_weird(struct dentry *dentry); diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h index 5b5a32116424..9642ec64467b 100644 --- a/fs/overlayfs/ovl_entry.h +++ b/fs/overlayfs/ovl_entry.h @@ -14,6 +14,7 @@ struct ovl_config { char *workdir; bool default_permissions; bool redirect_dir; + bool index; }; /* private information held for overlayfs's superblock */ @@ -25,6 +26,8 @@ struct ovl_fs { struct dentry *workbasedir; /* workdir is the 'work' directory under workbasedir */ struct dentry *workdir; + /* index directory listing overlay inodes by origin file handle */ + struct dentry *indexdir; long namelen; /* pathnames of lower and upper dirs, for show_options */ struct ovl_config config; diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index fea7bd496f2e..fa83b3245124 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -34,6 +34,11 @@ module_param_named(redirect_dir, ovl_redirect_dir_def, bool, 0644); MODULE_PARM_DESC(ovl_redirect_dir_def, "Default to on or off for the redirect_dir feature"); +static bool ovl_index_def = IS_ENABLED(CONFIG_OVERLAY_FS_INDEX); +module_param_named(index, ovl_index_def, bool, 0644); +MODULE_PARM_DESC(ovl_index_def, + "Default to on or off for the inodes index feature"); + static void ovl_dentry_release(struct dentry *dentry) { struct ovl_entry *oe = dentry->d_fsdata; @@ -203,6 +208,7 @@ static void ovl_put_super(struct super_block *sb) struct ovl_fs *ufs = sb->s_fs_info; unsigned i; + dput(ufs->indexdir); dput(ufs->workdir); ovl_inuse_unlock(ufs->workbasedir); dput(ufs->workbasedir); @@ -265,6 +271,12 @@ static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf) return err; } +/* Will this overlay be forced to mount/remount ro? */ +static bool ovl_force_readonly(struct ovl_fs *ufs) +{ + return (!ufs->upper_mnt || !ufs->workdir); +} + /** * ovl_show_options * @@ -286,6 +298,9 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry) if (ufs->config.redirect_dir != ovl_redirect_dir_def) seq_printf(m, ",redirect_dir=%s", ufs->config.redirect_dir ? "on" : "off"); + if (ufs->config.index != ovl_index_def) + seq_printf(m, ",index=%s", + ufs->config.index ? "on" : "off"); return 0; } @@ -293,7 +308,7 @@ static int ovl_remount(struct super_block *sb, int *flags, char *data) { struct ovl_fs *ufs = sb->s_fs_info; - if (!(*flags & MS_RDONLY) && (!ufs->upper_mnt || !ufs->workdir)) + if (!(*flags & MS_RDONLY) && ovl_force_readonly(ufs)) return -EROFS; return 0; @@ -317,6 +332,8 @@ enum { OPT_DEFAULT_PERMISSIONS, OPT_REDIRECT_DIR_ON, OPT_REDIRECT_DIR_OFF, + OPT_INDEX_ON, + OPT_INDEX_OFF, OPT_ERR, }; @@ -327,6 +344,8 @@ static const match_table_t ovl_tokens = { {OPT_DEFAULT_PERMISSIONS, "default_permissions"}, {OPT_REDIRECT_DIR_ON, "redirect_dir=on"}, {OPT_REDIRECT_DIR_OFF, "redirect_dir=off"}, + {OPT_INDEX_ON, "index=on"}, + {OPT_INDEX_OFF, "index=off"}, {OPT_ERR, NULL} }; @@ -399,6 +418,14 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) config->redirect_dir = false; break; + case OPT_INDEX_ON: + config->index = true; + break; + + case OPT_INDEX_OFF: + config->index = false; + break; + default: pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p); return -EINVAL; @@ -417,6 +444,7 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) } #define OVL_WORKDIR_NAME "work" +#define OVL_INDEXDIR_NAME "index" static struct dentry *ovl_workdir_create(struct super_block *sb, struct ovl_fs *ufs, @@ -610,6 +638,15 @@ static int ovl_lower_dir(const char *name, struct path *path, if (ovl_dentry_remote(path->dentry)) *remote = true; + /* + * The inodes index feature needs to encode and decode file + * handles, so it requires that all layers support them. + */ + if (ofs->config.index && !ovl_can_decode_fh(path->dentry->d_sb)) { + ofs->config.index = false; + pr_warn("overlayfs: fs on '%s' does not support file handles, falling back to index=off.\n", name); + } + return 0; out_put: @@ -807,6 +844,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) goto out; ufs->config.redirect_dir = ovl_redirect_dir_def; + ufs->config.index = ovl_index_def; err = ovl_parse_opt((char *) data, &ufs->config); if (err) goto out_free_config; @@ -965,6 +1003,13 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) } else { vfs_removexattr(ufs->workdir, OVL_XATTR_OPAQUE); } + + /* Check if upper/work fs supports file handles */ + if (ufs->config.index && + !ovl_can_decode_fh(ufs->workdir->d_sb)) { + ufs->config.index = false; + pr_warn("overlayfs: upper fs does not support file handles, falling back to index=off.\n"); + } } } @@ -1002,6 +1047,21 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) else if (ufs->upper_mnt->mnt_sb != ufs->same_sb) ufs->same_sb = NULL; + if (!(ovl_force_readonly(ufs)) && ufs->config.index) { + ufs->indexdir = ovl_workdir_create(sb, ufs, workpath.dentry, + OVL_INDEXDIR_NAME, true); + err = PTR_ERR(ufs->indexdir); + if (IS_ERR(ufs->indexdir)) + goto out_put_lower_mnt; + + if (!ufs->indexdir) + pr_warn("overlayfs: try deleting index dir or mounting with '-o index=off' to disable inodes index.\n"); + } + + /* Show index=off/on in /proc/mounts for any of the reasons above */ + if (!ufs->indexdir) + ufs->config.index = false; + if (remote) sb->s_d_op = &ovl_reval_dentry_operations; else @@ -1009,7 +1069,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) ufs->creator_cred = cred = prepare_creds(); if (!cred) - goto out_put_lower_mnt; + goto out_put_indexdir; /* Never override disk quota limits or use reserved space */ cap_lower(cred->cap_effective, CAP_SYS_RESOURCE); @@ -1058,6 +1118,8 @@ out_free_oe: kfree(oe); out_put_cred: put_cred(ufs->creator_cred); +out_put_indexdir: + dput(ufs->indexdir); out_put_lower_mnt: for (i = 0; i < ufs->numlower; i++) mntput(ufs->lower_mnt[i]); diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c index adccd74162d6..90b50b8e75ab 100644 --- a/fs/overlayfs/util.c +++ b/fs/overlayfs/util.c @@ -12,6 +12,8 @@ #include <linux/slab.h> #include <linux/cred.h> #include <linux/xattr.h> +#include <linux/exportfs.h> +#include <linux/uuid.h> #include "overlayfs.h" #include "ovl_entry.h" @@ -47,6 +49,19 @@ struct super_block *ovl_same_sb(struct super_block *sb) return ofs->same_sb; } +bool ovl_can_decode_fh(struct super_block *sb) +{ + return (sb->s_export_op && sb->s_export_op->fh_to_dentry && + !uuid_is_null(&sb->s_uuid)); +} + +struct dentry *ovl_indexdir(struct super_block *sb) +{ + struct ovl_fs *ofs = sb->s_fs_info; + + return ofs->indexdir; +} + struct ovl_entry *ovl_alloc_entry(unsigned int numlower) { size_t size = offsetof(struct ovl_entry, lowerstack[numlower]); |