From 07f1e59637a8e5a8bddba5da7567d46635da510f Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Tue, 14 Jan 2020 21:59:22 +0200 Subject: [PATCH] ovl: generalize the lower_fs[] array Rename lower_fs[] array to fs[], extend its size by one and use index fsid (instead of fsid-1) to access the fs[] array. Initialize fs[0] with upper fs values. fsid 0 is reserved even with lower only overlay, so fs[0] remains null in this case. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi --- fs/overlayfs/inode.c | 21 ++++++------- fs/overlayfs/ovl_entry.h | 6 ++-- fs/overlayfs/super.c | 65 +++++++++++++++++++++------------------- 3 files changed, 46 insertions(+), 46 deletions(-) diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index cf51fa1e45a80..60f7b8f092f23 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -75,8 +75,7 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr) return err; } -static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat, - struct ovl_layer *lower_layer) +static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat, int fsid) { bool samefs = ovl_same_fs(dentry->d_sb); unsigned int xinobits = ovl_xino_bits(dentry->d_sb); @@ -103,9 +102,7 @@ static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat, pr_warn_ratelimited("inode number too big (%pd2, ino=%llu, xinobits=%d)\n", dentry, stat->ino, xinobits); } else { - if (lower_layer) - stat->ino |= ((u64)lower_layer->fsid) << shift; - + stat->ino |= ((u64)fsid) << shift; stat->dev = dentry->d_sb->s_dev; return 0; } @@ -124,7 +121,7 @@ static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat, */ stat->dev = dentry->d_sb->s_dev; stat->ino = dentry->d_inode->i_ino; - } else if (lower_layer && lower_layer->fsid) { + } else if (fsid) { /* * For non-samefs setup, if we cannot map all layers st_ino * to a unified address space, we need to make sure that st_dev @@ -132,7 +129,7 @@ static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat, * lower layers use the unique anonymous bdev assigned to the * lower fs. */ - stat->dev = lower_layer->fs->pseudo_dev; + stat->dev = OVL_FS(dentry->d_sb)->fs[fsid].pseudo_dev; } return 0; @@ -147,7 +144,7 @@ int ovl_getattr(const struct path *path, struct kstat *stat, const struct cred *old_cred; bool is_dir = S_ISDIR(dentry->d_inode->i_mode); bool samefs = ovl_same_fs(dentry->d_sb); - struct ovl_layer *lower_layer = NULL; + int fsid = 0; int err; bool metacopy_blocks = false; @@ -170,7 +167,7 @@ int ovl_getattr(const struct path *path, struct kstat *stat, */ if (!is_dir || ovl_same_dev(dentry->d_sb)) { if (!OVL_TYPE_UPPER(type)) { - lower_layer = ovl_layer_lower(dentry); + fsid = ovl_layer_lower(dentry)->fsid; } else if (OVL_TYPE_ORIGIN(type)) { struct kstat lowerstat; u32 lowermask = STATX_INO | STATX_BLOCKS | @@ -200,13 +197,13 @@ int ovl_getattr(const struct path *path, struct kstat *stat, if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) || (!ovl_verify_lower(dentry->d_sb) && (is_dir || lowerstat.nlink == 1))) { - lower_layer = ovl_layer_lower(dentry); + fsid = ovl_layer_lower(dentry)->fsid; /* * Cannot use origin st_dev;st_ino because * origin inode content may differ from overlay * inode content. */ - if (samefs || lower_layer->fsid) + if (samefs || fsid) stat->ino = lowerstat.ino; } @@ -241,7 +238,7 @@ int ovl_getattr(const struct path *path, struct kstat *stat, } } - err = ovl_map_dev_ino(dentry, stat, lower_layer); + err = ovl_map_dev_ino(dentry, stat, fsid); if (err) goto out; diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h index 9a785702a2a41..d9fbebdb60761 100644 --- a/fs/overlayfs/ovl_entry.h +++ b/fs/overlayfs/ovl_entry.h @@ -46,10 +46,10 @@ struct ovl_path { struct ovl_fs { struct vfsmount *upper_mnt; unsigned int numlayer; - /* Number of unique lower sb that differ from upper sb */ - unsigned int numlowerfs; + /* Number of unique fs among layers including upper fs */ + unsigned int numfs; struct ovl_layer *layers; - struct ovl_sb *lower_fs; + struct ovl_sb *fs; /* workbasedir is the path at workdir= mount option */ struct dentry *workbasedir; /* workdir is the 'work' directory under workbasedir */ diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 8f08313eb897b..d7c406d8c793d 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -228,10 +228,11 @@ static void ovl_free_fs(struct ovl_fs *ofs) iput(ofs->layers[i].trap); mntput(ofs->layers[i].mnt); } - for (i = 0; i < ofs->numlowerfs; i++) - free_anon_bdev(ofs->lower_fs[i].pseudo_dev); kfree(ofs->layers); - kfree(ofs->lower_fs); + /* fs[0].pseudo_dev is either null or real upper st_dev */ + for (i = 1; i < ofs->numfs; i++) + free_anon_bdev(ofs->fs[i].pseudo_dev); + kfree(ofs->fs); kfree(ofs->config.lowerdir); kfree(ofs->config.upperdir); @@ -1259,7 +1260,7 @@ static bool ovl_lower_uuid_ok(struct ovl_fs *ofs, const uuid_t *uuid) if (!ofs->config.nfs_export && !ofs->upper_mnt) return true; - for (i = 0; i < ofs->numlowerfs; i++) { + for (i = 1; i < ofs->numfs; i++) { /* * We use uuid to associate an overlay lower file handle with a * lower layer, so we can accept lower fs with null uuid as long @@ -1267,8 +1268,8 @@ static bool ovl_lower_uuid_ok(struct ovl_fs *ofs, const uuid_t *uuid) * if we detect multiple lower fs with the same uuid, we * disable lower file handle decoding on all of them. */ - if (uuid_equal(&ofs->lower_fs[i].sb->s_uuid, uuid)) { - ofs->lower_fs[i].bad_uuid = true; + if (uuid_equal(&ofs->fs[i].sb->s_uuid, uuid)) { + ofs->fs[i].bad_uuid = true; return false; } } @@ -1284,13 +1285,9 @@ static int ovl_get_fsid(struct ovl_fs *ofs, const struct path *path) int err; bool bad_uuid = false; - /* fsid 0 is reserved for upper fs even with non upper overlay */ - if (ofs->upper_mnt && ofs->upper_mnt->mnt_sb == sb) - return 0; - - for (i = 0; i < ofs->numlowerfs; i++) { - if (ofs->lower_fs[i].sb == sb) - return i + 1; + for (i = 0; i < ofs->numfs; i++) { + if (ofs->fs[i].sb == sb) + return i; } if (!ovl_lower_uuid_ok(ofs, &sb->s_uuid)) { @@ -1311,12 +1308,11 @@ static int ovl_get_fsid(struct ovl_fs *ofs, const struct path *path) return err; } - ofs->lower_fs[ofs->numlowerfs].sb = sb; - ofs->lower_fs[ofs->numlowerfs].pseudo_dev = dev; - ofs->lower_fs[ofs->numlowerfs].bad_uuid = bad_uuid; - ofs->numlowerfs++; + ofs->fs[ofs->numfs].sb = sb; + ofs->fs[ofs->numfs].pseudo_dev = dev; + ofs->fs[ofs->numfs].bad_uuid = bad_uuid; - return ofs->numlowerfs; + return ofs->numfs++; } static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, @@ -1331,17 +1327,27 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, if (ofs->layers == NULL) goto out; - ofs->lower_fs = kcalloc(numlower, sizeof(struct ovl_sb), - GFP_KERNEL); - if (ofs->lower_fs == NULL) + ofs->fs = kcalloc(numlower + 1, sizeof(struct ovl_sb), GFP_KERNEL); + if (ofs->fs == NULL) goto out; - /* idx 0 is reserved for upper fs even with lower only overlay */ + /* idx/fsid 0 are reserved for upper fs even with lower only overlay */ + ofs->numfs++; + ofs->layers[0].mnt = ofs->upper_mnt; ofs->layers[0].idx = 0; ofs->layers[0].fsid = 0; ofs->numlayer = 1; + /* + * All lower layers that share the same fs as upper layer, use the real + * upper st_dev. + */ + if (ofs->upper_mnt) { + ofs->fs[0].sb = ofs->upper_mnt->mnt_sb; + ofs->fs[0].pseudo_dev = ofs->upper_mnt->mnt_sb->s_dev; + } + for (i = 0; i < numlower; i++) { struct vfsmount *mnt; struct inode *trap; @@ -1379,10 +1385,7 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, ofs->layers[ofs->numlayer].mnt = mnt; ofs->layers[ofs->numlayer].idx = ofs->numlayer; ofs->layers[ofs->numlayer].fsid = fsid; - if (fsid) { - ofs->layers[ofs->numlayer].fs = - &ofs->lower_fs[fsid - 1]; - } + ofs->layers[ofs->numlayer].fs = &ofs->fs[fsid]; ofs->numlayer++; } @@ -1394,18 +1397,18 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, * bits reserved for fsid, it emits a warning and uses the original * inode number. */ - if (!ofs->numlowerfs || (ofs->numlowerfs == 1 && !ofs->upper_mnt)) { + if (ofs->numfs - !ofs->upper_mnt == 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; } else if (ofs->config.xino == OVL_XINO_ON && ofs->xino_mode < 0) { /* - * 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. + * This is a roundup of number of bits needed for encoding + * fsid, where fsid 0 is reserved for upper fs even with + * lower only overlay. */ BUILD_BUG_ON(ilog2(OVL_MAX_STACK) > 31); - ofs->xino_mode = ilog2(ofs->numlowerfs) + 1; + ofs->xino_mode = ilog2(ofs->numfs - 1) + 1; } if (ofs->xino_mode > 0) {