ovl: make private mounts longterm
[linux-2.6-microblaze.git] / fs / overlayfs / super.c
index af69f41..8d8cd46 100644 (file)
@@ -211,24 +211,28 @@ static void ovl_destroy_inode(struct inode *inode)
 
 static void ovl_free_fs(struct ovl_fs *ofs)
 {
+       struct vfsmount **mounts;
        unsigned i;
 
        iput(ofs->workbasedir_trap);
        iput(ofs->indexdir_trap);
        iput(ofs->workdir_trap);
-       iput(ofs->upperdir_trap);
+       dput(ofs->whiteout);
        dput(ofs->indexdir);
        dput(ofs->workdir);
        if (ofs->workdir_locked)
                ovl_inuse_unlock(ofs->workbasedir);
        dput(ofs->workbasedir);
        if (ofs->upperdir_locked)
-               ovl_inuse_unlock(ofs->upper_mnt->mnt_root);
-       mntput(ofs->upper_mnt);
-       for (i = 1; i < ofs->numlayer; i++) {
+               ovl_inuse_unlock(ovl_upper_mnt(ofs)->mnt_root);
+
+       /* Hack!  Reuse ofs->layers as a vfsmount array before freeing it */
+       mounts = (struct vfsmount **) ofs->layers;
+       for (i = 0; i < ofs->numlayer; i++) {
                iput(ofs->layers[i].trap);
-               mntput(ofs->layers[i].mnt);
+               mounts[i] = ofs->layers[i].mnt;
        }
+       kern_unmount_array(mounts, ofs->numlayer);
        kfree(ofs->layers);
        for (i = 0; i < ofs->numfs; i++)
                free_anon_bdev(ofs->fs[i].pseudo_dev);
@@ -257,7 +261,7 @@ static int ovl_sync_fs(struct super_block *sb, int wait)
        struct super_block *upper_sb;
        int ret;
 
-       if (!ofs->upper_mnt)
+       if (!ovl_upper_mnt(ofs))
                return 0;
 
        /*
@@ -271,7 +275,7 @@ static int ovl_sync_fs(struct super_block *sb, int wait)
        if (!wait)
                return 0;
 
-       upper_sb = ofs->upper_mnt->mnt_sb;
+       upper_sb = ovl_upper_mnt(ofs)->mnt_sb;
 
        down_read(&upper_sb->s_umount);
        ret = sync_filesystem(upper_sb);
@@ -309,7 +313,7 @@ static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
 /* Will this overlay be forced to mount/remount ro? */
 static bool ovl_force_readonly(struct ovl_fs *ofs)
 {
-       return (!ofs->upper_mnt || !ofs->workdir);
+       return (!ovl_upper_mnt(ofs) || !ofs->workdir);
 }
 
 static const char *ovl_redirect_mode_def(void)
@@ -364,11 +368,20 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
 static int ovl_remount(struct super_block *sb, int *flags, char *data)
 {
        struct ovl_fs *ofs = sb->s_fs_info;
+       struct super_block *upper_sb;
+       int ret = 0;
 
        if (!(*flags & SB_RDONLY) && ovl_force_readonly(ofs))
                return -EROFS;
 
-       return 0;
+       if (*flags & SB_RDONLY && !sb_rdonly(sb)) {
+               upper_sb = ovl_upper_mnt(ofs)->mnt_sb;
+               down_read(&upper_sb->s_umount);
+               ret = sync_filesystem(upper_sb);
+               up_read(&upper_sb->s_umount);
+       }
+
+       return ret;
 }
 
 static const struct super_operations ovl_super_operations = {
@@ -659,7 +672,7 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
                                         const char *name, bool persist)
 {
        struct inode *dir =  ofs->workbasedir->d_inode;
-       struct vfsmount *mnt = ofs->upper_mnt;
+       struct vfsmount *mnt = ovl_upper_mnt(ofs);
        struct dentry *work;
        int err;
        bool retried = false;
@@ -827,11 +840,11 @@ static int ovl_lower_dir(const char *name, struct path *path,
 
        err = ovl_mount_dir_noesc(name, path);
        if (err)
-               goto out;
+               return err;
 
        err = ovl_check_namelen(path, ofs, name);
        if (err)
-               goto out_put;
+               return err;
 
        *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);
 
@@ -853,11 +866,6 @@ static int ovl_lower_dir(const char *name, struct path *path,
                ofs->xino_mode = -1;
 
        return 0;
-
-out_put:
-       path_put_init(path);
-out:
-       return err;
 }
 
 /* Workdir should not be subdir of upperdir and vice versa */
@@ -1064,7 +1072,7 @@ static int ovl_report_in_use(struct ovl_fs *ofs, const char *name)
 }
 
 static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs,
-                        struct path *upperpath)
+                        struct ovl_layer *upper_layer, struct path *upperpath)
 {
        struct vfsmount *upper_mnt;
        int err;
@@ -1084,7 +1092,7 @@ static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs,
        if (err)
                goto out;
 
-       err = ovl_setup_trap(sb, upperpath->dentry, &ofs->upperdir_trap,
+       err = ovl_setup_trap(sb, upperpath->dentry, &upper_layer->trap,
                             "upperdir");
        if (err)
                goto out;
@@ -1098,7 +1106,9 @@ static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs,
 
        /* Don't inherit atime flags */
        upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME);
-       ofs->upper_mnt = upper_mnt;
+       upper_layer->mnt = upper_mnt;
+       upper_layer->idx = 0;
+       upper_layer->fsid = 0;
 
        /*
         * Inherit SB_NOSEC flag from upperdir.
@@ -1112,7 +1122,7 @@ static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs,
        if (upper_mnt->mnt_sb->s_flags & SB_NOSEC)
                sb->s_flags |= SB_NOSEC;
 
-       if (ovl_inuse_trylock(ofs->upper_mnt->mnt_root)) {
+       if (ovl_inuse_trylock(ovl_upper_mnt(ofs)->mnt_root)) {
                ofs->upperdir_locked = true;
        } else {
                err = ovl_report_in_use(ofs, "upperdir");
@@ -1188,7 +1198,7 @@ out_unlock:
 static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs,
                            struct path *workpath)
 {
-       struct vfsmount *mnt = ofs->upper_mnt;
+       struct vfsmount *mnt = ovl_upper_mnt(ofs);
        struct dentry *temp;
        bool rename_whiteout;
        bool d_type;
@@ -1332,7 +1342,7 @@ out:
 static int ovl_get_indexdir(struct super_block *sb, struct ovl_fs *ofs,
                            struct ovl_entry *oe, struct path *upperpath)
 {
-       struct vfsmount *mnt = ofs->upper_mnt;
+       struct vfsmount *mnt = ovl_upper_mnt(ofs);
        int err;
 
        err = mnt_want_write(mnt);
@@ -1388,7 +1398,7 @@ static bool ovl_lower_uuid_ok(struct ovl_fs *ofs, const uuid_t *uuid)
 {
        unsigned int i;
 
-       if (!ofs->config.nfs_export && !ofs->upper_mnt)
+       if (!ofs->config.nfs_export && !ovl_upper_mnt(ofs))
                return true;
 
        for (i = 0; i < ofs->numfs; i++) {
@@ -1448,18 +1458,13 @@ static int ovl_get_fsid(struct ovl_fs *ofs, const struct path *path)
 }
 
 static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
-                         struct path *stack, unsigned int numlower)
+                         struct path *stack, unsigned int numlower,
+                         struct ovl_layer *layers)
 {
        int err;
        unsigned int i;
-       struct ovl_layer *layers;
 
        err = -ENOMEM;
-       layers = kcalloc(numlower + 1, sizeof(struct ovl_layer), GFP_KERNEL);
-       if (!layers)
-               goto out;
-       ofs->layers = layers;
-
        ofs->fs = kcalloc(numlower + 1, sizeof(struct ovl_sb), GFP_KERNEL);
        if (ofs->fs == NULL)
                goto out;
@@ -1467,11 +1472,6 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
        /* idx/fsid 0 are reserved for upper fs even with lower only overlay */
        ofs->numfs++;
 
-       layers[0].mnt = ofs->upper_mnt;
-       layers[0].idx = 0;
-       layers[0].fsid = 0;
-       ofs->numlayer = 1;
-
        /*
         * All lower layers that share the same fs as upper layer, use the same
         * pseudo_dev as upper layer.  Allocate fs[0].pseudo_dev even for lower
@@ -1484,8 +1484,8 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
                goto out;
        }
 
-       if (ofs->upper_mnt) {
-               ofs->fs[0].sb = ofs->upper_mnt->mnt_sb;
+       if (ovl_upper_mnt(ofs)) {
+               ofs->fs[0].sb = ovl_upper_mnt(ofs)->mnt_sb;
                ofs->fs[0].is_lower = false;
        }
 
@@ -1540,7 +1540,7 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
         * inode number or a non persistent inode number allocated from a
         * dedicated range.
         */
-       if (ofs->numfs - !ofs->upper_mnt == 1) {
+       if (ofs->numfs - !ovl_upper_mnt(ofs) == 1) {
                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;
@@ -1569,44 +1569,30 @@ out:
 }
 
 static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
-                                           struct ovl_fs *ofs)
+                               const char *lower, unsigned int numlower,
+                               struct ovl_fs *ofs, struct ovl_layer *layers)
 {
        int err;
-       char *lowertmp, *lower;
        struct path *stack = NULL;
-       unsigned int stacklen, numlower = 0, i;
+       unsigned int i;
        struct ovl_entry *oe;
 
-       err = -ENOMEM;
-       lowertmp = kstrdup(ofs->config.lowerdir, GFP_KERNEL);
-       if (!lowertmp)
-               goto out_err;
-
-       err = -EINVAL;
-       stacklen = ovl_split_lowerdirs(lowertmp);
-       if (stacklen > OVL_MAX_STACK) {
-               pr_err("too many lower directories, limit is %d\n",
-                      OVL_MAX_STACK);
-               goto out_err;
-       } else if (!ofs->config.upperdir && stacklen == 1) {
+       if (!ofs->config.upperdir && numlower == 1) {
                pr_err("at least 2 lowerdir are needed while upperdir nonexistent\n");
-               goto out_err;
+               return ERR_PTR(-EINVAL);
        } else if (!ofs->config.upperdir && ofs->config.nfs_export &&
                   ofs->config.redirect_follow) {
                pr_warn("NFS export requires \"redirect_dir=nofollow\" on non-upper mount, falling back to nfs_export=off.\n");
                ofs->config.nfs_export = false;
        }
 
-       err = -ENOMEM;
-       stack = kcalloc(stacklen, sizeof(struct path), GFP_KERNEL);
+       stack = kcalloc(numlower, sizeof(struct path), GFP_KERNEL);
        if (!stack)
-               goto out_err;
+               return ERR_PTR(-ENOMEM);
 
        err = -EINVAL;
-       lower = lowertmp;
-       for (numlower = 0; numlower < stacklen; numlower++) {
-               err = ovl_lower_dir(lower, &stack[numlower], ofs,
-                                   &sb->s_stack_depth);
+       for (i = 0; i < numlower; i++) {
+               err = ovl_lower_dir(lower, &stack[i], ofs, &sb->s_stack_depth);
                if (err)
                        goto out_err;
 
@@ -1620,7 +1606,7 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
                goto out_err;
        }
 
-       err = ovl_get_layers(sb, ofs, stack, numlower);
+       err = ovl_get_layers(sb, ofs, stack, numlower, layers);
        if (err)
                goto out_err;
 
@@ -1638,7 +1624,6 @@ out:
        for (i = 0; i < numlower; i++)
                path_put(&stack[i]);
        kfree(stack);
-       kfree(lowertmp);
 
        return oe;
 
@@ -1689,8 +1674,8 @@ static int ovl_check_overlapping_layers(struct super_block *sb,
 {
        int i, err;
 
-       if (ofs->upper_mnt) {
-               err = ovl_check_layer(sb, ofs, ofs->upper_mnt->mnt_root,
+       if (ovl_upper_mnt(ofs)) {
+               err = ovl_check_layer(sb, ofs, ovl_upper_mnt(ofs)->mnt_root,
                                      "upperdir");
                if (err)
                        return err;
@@ -1762,7 +1747,10 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
        struct dentry *root_dentry;
        struct ovl_entry *oe;
        struct ovl_fs *ofs;
+       struct ovl_layer *layers;
        struct cred *cred;
+       char *splitlower = NULL;
+       unsigned int numlower;
        int err;
 
        sb->s_d_op = &ovl_dentry_operations;
@@ -1776,6 +1764,9 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
        if (!cred)
                goto out_err;
 
+       /* Is there a reason anyone would want not to share whiteouts? */
+       ofs->share_whiteout = true;
+
        ofs->config.index = ovl_index_def;
        ofs->config.nfs_export = ovl_nfs_export_def;
        ofs->config.xino = ovl_xino_def();
@@ -1791,6 +1782,26 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
                goto out_err;
        }
 
+       err = -ENOMEM;
+       splitlower = kstrdup(ofs->config.lowerdir, GFP_KERNEL);
+       if (!splitlower)
+               goto out_err;
+
+       numlower = ovl_split_lowerdirs(splitlower);
+       if (numlower > OVL_MAX_STACK) {
+               pr_err("too many lower directories, limit is %d\n",
+                      OVL_MAX_STACK);
+               goto out_err;
+       }
+
+       layers = kcalloc(numlower + 1, sizeof(struct ovl_layer), GFP_KERNEL);
+       if (!layers)
+               goto out_err;
+
+       ofs->layers = layers;
+       /* Layer 0 is reserved for upper even if there's no upper */
+       ofs->numlayer = 1;
+
        sb->s_stack_depth = 0;
        sb->s_maxbytes = MAX_LFS_FILESIZE;
        atomic_long_set(&ofs->last_ino, 1);
@@ -1812,7 +1823,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
                        goto out_err;
                }
 
-               err = ovl_get_upper(sb, ofs, &upperpath);
+               err = ovl_get_upper(sb, ofs, &layers[0], &upperpath);
                if (err)
                        goto out_err;
 
@@ -1823,17 +1834,17 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
                if (!ofs->workdir)
                        sb->s_flags |= SB_RDONLY;
 
-               sb->s_stack_depth = ofs->upper_mnt->mnt_sb->s_stack_depth;
-               sb->s_time_gran = ofs->upper_mnt->mnt_sb->s_time_gran;
+               sb->s_stack_depth = ovl_upper_mnt(ofs)->mnt_sb->s_stack_depth;
+               sb->s_time_gran = ovl_upper_mnt(ofs)->mnt_sb->s_time_gran;
 
        }
-       oe = ovl_get_lowerstack(sb, ofs);
+       oe = ovl_get_lowerstack(sb, splitlower, numlower, ofs, layers);
        err = PTR_ERR(oe);
        if (IS_ERR(oe))
                goto out_err;
 
        /* If the upper fs is nonexistent, we mark overlayfs r/o too */
-       if (!ofs->upper_mnt)
+       if (!ovl_upper_mnt(ofs))
                sb->s_flags |= SB_RDONLY;
 
        if (!(ovl_force_readonly(ofs)) && ofs->config.index) {
@@ -1861,7 +1872,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
        /* Show index=off in /proc/mounts for forced r/o mount */
        if (!ofs->indexdir) {
                ofs->config.index = false;
-               if (ofs->upper_mnt && ofs->config.nfs_export) {
+               if (ovl_upper_mnt(ofs) && ofs->config.nfs_export) {
                        pr_warn("NFS export requires an index dir, falling back to nfs_export=off.\n");
                        ofs->config.nfs_export = false;
                }
@@ -1890,6 +1901,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
                goto out_free_oe;
 
        mntput(upperpath.mnt);
+       kfree(splitlower);
 
        sb->s_root = root_dentry;
 
@@ -1899,6 +1911,7 @@ out_free_oe:
        ovl_entry_stack_free(oe);
        kfree(oe);
 out_err:
+       kfree(splitlower);
        path_put(&upperpath);
        ovl_free_fs(ofs);
 out: