diff options
| -rw-r--r-- | fs/overlayfs/inode.c | 39 | ||||
| -rw-r--r-- | fs/overlayfs/readdir.c | 10 | ||||
| -rw-r--r-- | fs/overlayfs/super.c | 13 |
3 files changed, 45 insertions, 17 deletions
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index 8130ae54a332..2d6251a4caaf 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) { /* @@ -89,20 +90,20 @@ 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) { + if (unlikely(stat->ino >> xinoshift)) { pr_warn_ratelimited("inode number too big (%pd2, ino=%llu, xinobits=%d)\n", dentry, stat->ino, xinobits); } else { - stat->ino |= ((u64)fsid) << shift; + stat->ino |= ((u64)fsid) << (xinoshift + 1); stat->dev = dentry->d_sb->s_dev; return 0; } @@ -573,6 +574,7 @@ static void ovl_next_ino(struct inode *inode) 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 @@ -582,11 +584,28 @@ static void ovl_map_ino(struct inode *inode, unsigned long ino, int fsid) * with d_ino also causes nfsd readdirplus to fail. */ inode->i_ino = ino; - if (ovl_same_dev(inode->i_sb)) { - if (xinobits && fsid && !(ino >> (64 - xinobits))) - inode->i_ino |= (unsigned long)fsid << (64 - xinobits); - } else if (S_ISDIR(inode->i_mode)) { + 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; + } } } diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c index 40ac9ce2465a..6325dcc4c48b 100644 --- a/fs/overlayfs/readdir.c +++ b/fs/overlayfs/readdir.c @@ -440,13 +440,19 @@ static struct ovl_dir_cache *ovl_cache_get(struct dentry *dentry) static u64 ovl_remap_lower_ino(u64 ino, int xinobits, int fsid, const char *name, int namelen) { - if (ino >> (64 - xinobits)) { + unsigned int xinoshift = 64 - xinobits; + + if (unlikely(ino >> xinoshift)) { pr_warn_ratelimited("d_ino too big (%.*s, ino=%llu, xinobits=%d)\n", namelen, name, ino, xinobits); return ino; } - return ino | ((u64)fsid) << (64 - xinobits); + /* + * The lowest xinobit is reserved for mapping the non-peresistent inode + * numbers range, but this range is only exposed via st_ino, not here. + */ + return ino | ((u64)fsid) << (xinoshift + 1); } /* diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 1f1d40fc5e33..53dd094f970e 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -1483,7 +1483,8 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, * 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. + * inode number or a non persistent inode number allocated from a + * dedicated range. */ if (ofs->numfs - !ofs->upper_mnt == 1) { if (ofs->config.xino == OVL_XINO_ON) @@ -1494,11 +1495,13 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, } else if (ofs->config.xino == OVL_XINO_ON && ofs->xino_mode < 0) { /* * 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. + * fsid, where fsid 0 is reserved for upper fs (even with + * lower only overlay) +1 extra bit is reserved for the non + * persistent inode number range that is used for resolving + * xino lower bits overflow. */ - BUILD_BUG_ON(ilog2(OVL_MAX_STACK) > 31); - ofs->xino_mode = ilog2(ofs->numfs - 1) + 1; + BUILD_BUG_ON(ilog2(OVL_MAX_STACK) > 30); + ofs->xino_mode = ilog2(ofs->numfs - 1) + 2; } if (ofs->xino_mode > 0) { |