diff options
| -rw-r--r-- | fs/overlayfs/Kconfig | 17 | ||||
| -rw-r--r-- | fs/overlayfs/ovl_entry.h | 1 | ||||
| -rw-r--r-- | fs/overlayfs/super.c | 73 |
3 files changed, 88 insertions, 3 deletions
diff --git a/fs/overlayfs/Kconfig b/fs/overlayfs/Kconfig index ce6ff5a0a6e4..17032631c5cf 100644 --- a/fs/overlayfs/Kconfig +++ b/fs/overlayfs/Kconfig @@ -86,3 +86,20 @@ config OVERLAY_FS_NFS_EXPORT case basis with the "nfs_export=on" mount option. Say N unless you fully understand the consequences. + +config OVERLAY_FS_XINO_AUTO + bool "Overlayfs: auto enable inode number mapping" + default n + depends on OVERLAY_FS + help + If this config option is enabled then overlay filesystems will use + unused high bits in undelying filesystem inode numbers to map all + inodes to a unified address space. The mapped 64bit inode numbers + might not be compatible with applications that expect 32bit inodes. + + If compatibility with applications that expect 32bit inodes 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/ovl_entry.h b/fs/overlayfs/ovl_entry.h index 620bd20f9a22..41655a7d6894 100644 --- a/fs/overlayfs/ovl_entry.h +++ b/fs/overlayfs/ovl_entry.h @@ -18,6 +18,7 @@ struct ovl_config { const char *redirect_mode; bool index; bool nfs_export; + int xino; }; struct ovl_sb { diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index d7284444f404..e8551c97de51 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -51,6 +51,11 @@ module_param_named(nfs_export, ovl_nfs_export_def, bool, 0644); MODULE_PARM_DESC(ovl_nfs_export_def, "Default to on or off for the NFS export feature"); +static bool ovl_xino_auto_def = IS_ENABLED(CONFIG_OVERLAY_FS_XINO_AUTO); +module_param_named(xino_auto, ovl_xino_auto_def, bool, 0644); +MODULE_PARM_DESC(ovl_xino_auto_def, + "Auto enable xino feature"); + static void ovl_entry_stack_free(struct ovl_entry *oe) { unsigned int i; @@ -327,6 +332,23 @@ static const char *ovl_redirect_mode_def(void) return ovl_redirect_dir_def ? "on" : "off"; } +enum { + OVL_XINO_OFF, + OVL_XINO_AUTO, + OVL_XINO_ON, +}; + +static const char * const ovl_xino_str[] = { + "off", + "auto", + "on", +}; + +static inline int ovl_xino_def(void) +{ + return ovl_xino_auto_def ? OVL_XINO_AUTO : OVL_XINO_OFF; +} + /** * ovl_show_options * @@ -352,6 +374,8 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry) if (ofs->config.nfs_export != ovl_nfs_export_def) seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ? "on" : "off"); + if (ofs->config.xino != ovl_xino_def()) + seq_printf(m, ",xino=%s", ovl_xino_str[ofs->config.xino]); return 0; } @@ -386,6 +410,9 @@ enum { OPT_INDEX_OFF, OPT_NFS_EXPORT_ON, OPT_NFS_EXPORT_OFF, + OPT_XINO_ON, + OPT_XINO_OFF, + OPT_XINO_AUTO, OPT_ERR, }; @@ -399,6 +426,9 @@ static const match_table_t ovl_tokens = { {OPT_INDEX_OFF, "index=off"}, {OPT_NFS_EXPORT_ON, "nfs_export=on"}, {OPT_NFS_EXPORT_OFF, "nfs_export=off"}, + {OPT_XINO_ON, "xino=on"}, + {OPT_XINO_OFF, "xino=off"}, + {OPT_XINO_AUTO, "xino=auto"}, {OPT_ERR, NULL} }; @@ -513,6 +543,18 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) config->nfs_export = false; break; + case OPT_XINO_ON: + config->xino = OVL_XINO_ON; + break; + + case OPT_XINO_OFF: + config->xino = OVL_XINO_OFF; + break; + + case OPT_XINO_AUTO: + config->xino = OVL_XINO_AUTO; + break; + default: pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p); return -EINVAL; @@ -1197,9 +1239,31 @@ static int ovl_get_lower_layers(struct ovl_fs *ofs, struct path *stack, ofs->numlower++; } - /* When all layers on same fs, overlay can use real inode numbers */ - if (!ofs->numlowerfs || (ofs->numlowerfs == 1 && !ofs->upper_mnt)) + /* + * When all layers on same fs, overlay can use real inode numbers. + * With mount option "xino=on", mounter declares that there are enough + * free high bits in underlying fs to hold the unique fsid. + * If overlayfs does encounter underlying inodes using the high xino + * bits reserved for fsid, it emits a warning and uses the original + * inode number. + */ + if (!ofs->numlowerfs || (ofs->numlowerfs == 1 && !ofs->upper_mnt)) { ofs->xino_bits = 0; + ofs->config.xino = OVL_XINO_OFF; + } else if (ofs->config.xino == OVL_XINO_ON && !ofs->xino_bits) { + /* + * This is a roundup of number of bits needed for numlowerfs+1 + * (i.e. ilog2(numlowerfs+1 - 1) + 1). fsid 0 is reserved for + * upper fs even with non upper overlay. + */ + BUILD_BUG_ON(ilog2(OVL_MAX_STACK) > 31); + ofs->xino_bits = ilog2(ofs->numlowerfs) + 1; + } + + if (ofs->xino_bits) { + pr_info("overlayfs: \"xino\" feature enabled using %d upper inode bits.\n", + ofs->xino_bits); + } err = 0; out: @@ -1311,6 +1375,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) ofs->config.index = ovl_index_def; ofs->config.nfs_export = ovl_nfs_export_def; + ofs->config.xino = ovl_xino_def(); err = ovl_parse_opt((char *) data, &ofs->config); if (err) goto out_err; @@ -1325,7 +1390,9 @@ 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 */ - ofs->xino_bits = BITS_PER_LONG - 32; + if (ofs->config.xino != OVL_XINO_OFF) + ofs->xino_bits = BITS_PER_LONG - 32; + if (ofs->config.upperdir) { if (!ofs->config.workdir) { pr_err("overlayfs: missing 'workdir'\n"); |