diff options
Diffstat (limited to 'fs/overlayfs/inode.c')
-rw-r--r-- | fs/overlayfs/inode.c | 99 |
1 files changed, 74 insertions, 25 deletions
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index 79e8994e3bc1..b0d42ece4d7c 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -79,6 +79,7 @@ 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); + unsigned int xinoshift = 64 - xinobits; if (samefs) { /* @@ -89,22 +90,22 @@ static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat, int fsid) stat->dev = dentry->d_sb->s_dev; return 0; } else if (xinobits) { - unsigned int shift = 64 - xinobits; /* * All inode numbers of underlying fs should not be using the * high xinobits, so we use high xinobits to partition the * overlay st_ino address space. The high bits holds the fsid - * (upper fsid is 0). This way overlay inode numbers are unique - * and all inodes use overlay st_dev. Inode numbers are also - * persistent for a given layer configuration. + * (upper fsid is 0). The lowest xinobit is reserved for mapping + * the non-peresistent inode numbers range in case of overflow. + * This way all overlay inode numbers are unique and use the + * overlay st_dev. */ - if (stat->ino >> shift) { - pr_warn_ratelimited("inode number too big (%pd2, ino=%llu, xinobits=%d)\n", - dentry, stat->ino, xinobits); - } else { - stat->ino |= ((u64)fsid) << shift; + if (likely(!(stat->ino >> xinoshift))) { + stat->ino |= ((u64)fsid) << (xinoshift + 1); stat->dev = dentry->d_sb->s_dev; return 0; + } else if (ovl_xino_warn(dentry->d_sb)) { + pr_warn_ratelimited("inode number too big (%pd2, ino=%llu, xinobits=%d)\n", + dentry, stat->ino, xinobits); } } @@ -504,7 +505,7 @@ static const struct address_space_operations ovl_aops = { /* * It is possible to stack overlayfs instance on top of another - * overlayfs instance as lower layer. We need to annonate the + * overlayfs instance as lower layer. We need to annotate the * stackable i_mutex locks according to stack level of the super * block instance. An overlayfs instance can never be in stack * depth 0 (there is always a real fs below it). An overlayfs @@ -561,27 +562,73 @@ static inline void ovl_lockdep_annotate_inode_mutex_key(struct inode *inode) #endif } -static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev, - unsigned long ino, int fsid) +static void ovl_next_ino(struct inode *inode) +{ + struct ovl_fs *ofs = inode->i_sb->s_fs_info; + + inode->i_ino = atomic_long_inc_return(&ofs->last_ino); + if (unlikely(!inode->i_ino)) + inode->i_ino = atomic_long_inc_return(&ofs->last_ino); +} + +static void ovl_map_ino(struct inode *inode, unsigned long ino, int fsid) { int xinobits = ovl_xino_bits(inode->i_sb); + unsigned int xinoshift = 64 - xinobits; /* * When d_ino is consistent with st_ino (samefs or i_ino has enough * bits to encode layer), set the same value used for st_ino to i_ino, * so inode number exposed via /proc/locks and a like will be * consistent with d_ino and st_ino values. An i_ino value inconsistent - * with d_ino also causes nfsd readdirplus to fail. When called from - * ovl_new_inode(), ino arg is 0, so i_ino will be updated to real - * upper inode i_ino on ovl_inode_init() or ovl_inode_update(). + * with d_ino also causes nfsd readdirplus to fail. */ - if (ovl_same_dev(inode->i_sb)) { - inode->i_ino = ino; - if (xinobits && fsid && !(ino >> (64 - xinobits))) - inode->i_ino |= (unsigned long)fsid << (64 - xinobits); - } else { - inode->i_ino = get_next_ino(); + inode->i_ino = ino; + if (ovl_same_fs(inode->i_sb)) { + return; + } else if (xinobits && likely(!(ino >> xinoshift))) { + inode->i_ino |= (unsigned long)fsid << (xinoshift + 1); + return; + } + + /* + * For directory inodes on non-samefs with xino disabled or xino + * overflow, we allocate a non-persistent inode number, to be used for + * resolving st_ino collisions in ovl_map_dev_ino(). + * + * To avoid ino collision with legitimate xino values from upper + * layer (fsid 0), use the lowest xinobit to map the non + * persistent inode numbers to the unified st_ino address space. + */ + if (S_ISDIR(inode->i_mode)) { + ovl_next_ino(inode); + if (xinobits) { + inode->i_ino &= ~0UL >> xinobits; + inode->i_ino |= 1UL << xinoshift; + } } +} + +void ovl_inode_init(struct inode *inode, struct ovl_inode_params *oip, + unsigned long ino, int fsid) +{ + struct inode *realinode; + + if (oip->upperdentry) + OVL_I(inode)->__upperdentry = oip->upperdentry; + if (oip->lowerpath && oip->lowerpath->dentry) + OVL_I(inode)->lower = igrab(d_inode(oip->lowerpath->dentry)); + if (oip->lowerdata) + OVL_I(inode)->lowerdata = igrab(d_inode(oip->lowerdata)); + + realinode = ovl_inode_real(inode); + ovl_copyattr(realinode, inode); + ovl_copyflags(realinode, inode); + ovl_map_ino(inode, ino, fsid); +} + +static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev) +{ inode->i_mode = mode; inode->i_flags |= S_NOCMTIME; #ifdef CONFIG_FS_POSIX_ACL @@ -719,7 +766,7 @@ struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev) inode = new_inode(sb); if (inode) - ovl_fill_inode(inode, mode, rdev, 0, 0); + ovl_fill_inode(inode, mode, rdev); return inode; } @@ -891,7 +938,7 @@ struct inode *ovl_get_inode(struct super_block *sb, struct dentry *lowerdentry = lowerpath ? lowerpath->dentry : NULL; bool bylower = ovl_hash_bylower(sb, upperdentry, lowerdentry, oip->index); - int fsid = bylower ? oip->lowerpath->layer->fsid : 0; + int fsid = bylower ? lowerpath->layer->fsid : 0; bool is_dir, metacopy = false; unsigned long ino = 0; int err = oip->newinode ? -EEXIST : -ENOMEM; @@ -941,9 +988,11 @@ struct inode *ovl_get_inode(struct super_block *sb, err = -ENOMEM; goto out_err; } + ino = realinode->i_ino; + fsid = lowerpath->layer->fsid; } - ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev, ino, fsid); - ovl_inode_init(inode, upperdentry, lowerdentry, oip->lowerdata); + ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev); + ovl_inode_init(inode, oip, ino, fsid); if (upperdentry && ovl_is_impuredir(upperdentry)) ovl_set_flag(OVL_IMPURE, inode); |