diff options
Diffstat (limited to 'fs/overlayfs/util.c')
| -rw-r--r-- | fs/overlayfs/util.c | 146 |
1 files changed, 128 insertions, 18 deletions
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c index 89e0d60d35..cd0722309e 100644 --- a/fs/overlayfs/util.c +++ b/fs/overlayfs/util.c @@ -17,12 +17,38 @@ #include <linux/ratelimit.h> #include "overlayfs.h" +/* Get write access to upper mnt - may fail if upper sb was remounted ro */ +int ovl_get_write_access(struct dentry *dentry) +{ + struct ovl_fs *ofs = OVL_FS(dentry->d_sb); + return mnt_get_write_access(ovl_upper_mnt(ofs)); +} + +/* Get write access to upper sb - may block if upper sb is frozen */ +void ovl_start_write(struct dentry *dentry) +{ + struct ovl_fs *ofs = OVL_FS(dentry->d_sb); + sb_start_write(ovl_upper_mnt(ofs)->mnt_sb); +} + int ovl_want_write(struct dentry *dentry) { struct ovl_fs *ofs = OVL_FS(dentry->d_sb); return mnt_want_write(ovl_upper_mnt(ofs)); } +void ovl_put_write_access(struct dentry *dentry) +{ + struct ovl_fs *ofs = OVL_FS(dentry->d_sb); + mnt_put_write_access(ovl_upper_mnt(ofs)); +} + +void ovl_end_write(struct dentry *dentry) +{ + struct ovl_fs *ofs = OVL_FS(dentry->d_sb); + sb_end_write(ovl_upper_mnt(ofs)->mnt_sb); +} + void ovl_drop_write(struct dentry *dentry) { struct ovl_fs *ofs = OVL_FS(dentry->d_sb); @@ -55,7 +81,7 @@ int ovl_can_decode_fh(struct super_block *sb) if (!capable(CAP_DAC_READ_SEARCH)) return 0; - if (!sb->s_export_op || !sb->s_export_op->fh_to_dentry) + if (!exportfs_can_decode_fh(sb->s_export_op)) return 0; return sb->s_export_op->encode_fh ? -1 : FILEID_INO32_GEN; @@ -435,6 +461,33 @@ void ovl_dentry_set_opaque(struct dentry *dentry) ovl_dentry_set_flag(OVL_E_OPAQUE, dentry); } +bool ovl_dentry_has_xwhiteouts(struct dentry *dentry) +{ + return ovl_dentry_test_flag(OVL_E_XWHITEOUTS, dentry); +} + +void ovl_dentry_set_xwhiteouts(struct dentry *dentry) +{ + ovl_dentry_set_flag(OVL_E_XWHITEOUTS, dentry); +} + +/* + * ovl_layer_set_xwhiteouts() is called before adding the overlay dir + * dentry to dcache, while readdir of that same directory happens after + * the overlay dir dentry is in dcache, so if some cpu observes that + * ovl_dentry_is_xwhiteouts(), it will also observe layer->has_xwhiteouts + * for the layers where xwhiteouts marker was found in that merge dir. + */ +void ovl_layer_set_xwhiteouts(struct ovl_fs *ofs, + const struct ovl_layer *layer) +{ + if (layer->has_xwhiteouts) + return; + + /* Write once to read-mostly layer properties */ + ofs->layers[layer->idx].has_xwhiteouts = true; +} + /* * For hard links and decoded file handles, it's possible for ovl_dentry_upper() * to return positive, while there's no actual upper alias for the inode. @@ -575,6 +628,16 @@ bool ovl_is_whiteout(struct dentry *dentry) return inode && IS_WHITEOUT(inode); } +/* + * Use this over ovl_is_whiteout for upper and lower files, as it also + * handles overlay.whiteout xattr whiteout files. + */ +bool ovl_path_is_whiteout(struct ovl_fs *ofs, const struct path *path) +{ + return ovl_is_whiteout(path->dentry) || + ovl_path_check_xwhiteout_xattr(ofs, path); +} + struct file *ovl_path_open(const struct path *path, int flags) { struct inode *inode = d_inode(path->dentry); @@ -644,22 +707,36 @@ bool ovl_already_copied_up(struct dentry *dentry, int flags) return false; } +/* + * The copy up "transaction" keeps an elevated mnt write count on upper mnt, + * but leaves taking freeze protection on upper sb to lower level helpers. + */ int ovl_copy_up_start(struct dentry *dentry, int flags) { struct inode *inode = d_inode(dentry); int err; err = ovl_inode_lock_interruptible(inode); - if (!err && ovl_already_copied_up_locked(dentry, flags)) { + if (err) + return err; + + if (ovl_already_copied_up_locked(dentry, flags)) err = 1; /* Already copied up */ - ovl_inode_unlock(inode); - } + else + err = ovl_get_write_access(dentry); + if (err) + goto out_unlock; + return 0; + +out_unlock: + ovl_inode_unlock(inode); return err; } void ovl_copy_up_end(struct dentry *dentry) { + ovl_put_write_access(dentry); ovl_inode_unlock(d_inode(dentry)); } @@ -676,6 +753,19 @@ bool ovl_path_check_origin_xattr(struct ovl_fs *ofs, const struct path *path) return false; } +bool ovl_path_check_xwhiteout_xattr(struct ovl_fs *ofs, const struct path *path) +{ + struct dentry *dentry = path->dentry; + int res; + + /* xattr.whiteout must be a zero size regular file */ + if (!d_is_reg(dentry) || i_size_read(d_inode(dentry)) != 0) + return false; + + res = ovl_path_getxattr(ofs, path, OVL_XATTR_XWHITEOUT, NULL, 0); + return res >= 0; +} + /* * Load persistent uuid from xattr into s_uuid if found, or store a new * random generated value in s_uuid and in xattr. @@ -735,20 +825,17 @@ fail: return false; } -bool ovl_path_check_dir_xattr(struct ovl_fs *ofs, const struct path *path, - enum ovl_xattr ox) +char ovl_get_dir_xattr_val(struct ovl_fs *ofs, const struct path *path, + enum ovl_xattr ox) { int res; char val; if (!d_is_dir(path->dentry)) - return false; + return 0; res = ovl_path_getxattr(ofs, path, ox, &val, 1); - if (res == 1 && val == 'y') - return true; - - return false; + return res == 1 ? val : 0; } #define OVL_XATTR_OPAQUE_POSTFIX "opaque" @@ -760,6 +847,7 @@ bool ovl_path_check_dir_xattr(struct ovl_fs *ofs, const struct path *path, #define OVL_XATTR_UUID_POSTFIX "uuid" #define OVL_XATTR_METACOPY_POSTFIX "metacopy" #define OVL_XATTR_PROTATTR_POSTFIX "protattr" +#define OVL_XATTR_XWHITEOUT_POSTFIX "whiteout" #define OVL_XATTR_TAB_ENTRY(x) \ [x] = { [false] = OVL_XATTR_TRUSTED_PREFIX x ## _POSTFIX, \ @@ -775,6 +863,7 @@ const char *const ovl_xattr_table[][2] = { OVL_XATTR_TAB_ENTRY(OVL_XATTR_UUID), OVL_XATTR_TAB_ENTRY(OVL_XATTR_METACOPY), OVL_XATTR_TAB_ENTRY(OVL_XATTR_PROTATTR), + OVL_XATTR_TAB_ENTRY(OVL_XATTR_XWHITEOUT), }; int ovl_check_setxattr(struct ovl_fs *ofs, struct dentry *upperdentry, @@ -898,7 +987,7 @@ int ovl_set_protattr(struct inode *inode, struct dentry *upper, return 0; } -/** +/* * Caller must hold a reference to inode to prevent it from being freed while * it is marked inuse. */ @@ -973,12 +1062,18 @@ static void ovl_cleanup_index(struct dentry *dentry) struct dentry *index = NULL; struct inode *inode; struct qstr name = { }; + bool got_write = false; int err; err = ovl_get_index_name(ofs, lowerdentry, &name); if (err) goto fail; + err = ovl_want_write(dentry); + if (err) + goto fail; + + got_write = true; inode = d_inode(upperdentry); if (!S_ISDIR(inode->i_mode) && inode->i_nlink != 1) { pr_warn_ratelimited("cleanup linked index (%pd2, ino=%lu, nlink=%u)\n", @@ -1016,6 +1111,8 @@ static void ovl_cleanup_index(struct dentry *dentry) goto fail; out: + if (got_write) + ovl_drop_write(dentry); kfree(name.name); dput(index); return; @@ -1062,8 +1159,12 @@ int ovl_nlink_start(struct dentry *dentry) if (err) return err; + err = ovl_want_write(dentry); + if (err) + goto out_unlock; + if (d_is_dir(dentry) || !ovl_test_flag(OVL_INDEX, inode)) - goto out; + return 0; old_cred = ovl_override_creds(dentry->d_sb); /* @@ -1074,10 +1175,15 @@ int ovl_nlink_start(struct dentry *dentry) */ err = ovl_set_nlink_upper(dentry); revert_creds(old_cred); - -out: if (err) - ovl_inode_unlock(inode); + goto out_drop_write; + + return 0; + +out_drop_write: + ovl_drop_write(dentry); +out_unlock: + ovl_inode_unlock(inode); return err; } @@ -1086,6 +1192,8 @@ void ovl_nlink_end(struct dentry *dentry) { struct inode *inode = d_inode(dentry); + ovl_drop_write(dentry); + if (ovl_test_flag(OVL_INDEX, inode) && inode->i_nlink == 0) { const struct cred *old_cred; @@ -1403,14 +1511,16 @@ void ovl_copyattr(struct inode *inode) realinode = ovl_i_path_real(inode, &realpath); real_idmap = mnt_idmap(realpath.mnt); + spin_lock(&inode->i_lock); vfsuid = i_uid_into_vfsuid(real_idmap, realinode); vfsgid = i_gid_into_vfsgid(real_idmap, realinode); inode->i_uid = vfsuid_into_kuid(vfsuid); inode->i_gid = vfsgid_into_kgid(vfsgid); inode->i_mode = realinode->i_mode; - inode->i_atime = realinode->i_atime; - inode->i_mtime = realinode->i_mtime; + inode_set_atime_to_ts(inode, inode_get_atime(realinode)); + inode_set_mtime_to_ts(inode, inode_get_mtime(realinode)); inode_set_ctime_to_ts(inode, inode_get_ctime(realinode)); i_size_write(inode, i_size_read(realinode)); + spin_unlock(&inode->i_lock); } |