filesystem for various technical reasons. The expectation is that
many use cases will be able to ignore these differences.
-This approach is 'hybrid' because the objects that appear in the
-filesystem do not all appear to belong to that filesystem. In many
-cases an object accessed in the union will be indistinguishable
+
+Overlay objects
+---------------
+
+The overlay filesystem approach is 'hybrid', because the objects that
+appear in the filesystem do not always appear to belong to that filesystem.
+In many cases, an object accessed in the union will be indistinguishable
from accessing the corresponding object from the original filesystem.
This is most obvious from the 'st_dev' field returned by stat(2).
overlay objects will be distinguishable from the corresponding
objects in the original filesystem.
+On 64bit systems, even if all overlay layers are not on the same
+underlying filesystem, the same compliant behavior could be achieved
+with the "xino" feature. The "xino" feature composes a unique object
+identifier from the real object st_ino and an underlying fsid index.
+If all underlying filesystems support NFS file handles and export file
+handles with 32bit inode number encoding (e.g. ext4), overlay filesystem
+will use the high inode number bits for fsid. Even when the underlying
+filesystem uses 64bit inode numbers, users can still enable the "xino"
+feature with the "-o xino=on" overlay mount option. That is useful for the
+case of underlying filesystems like xfs and tmpfs, which use 64bit inode
+numbers, but are very unlikely to use the high inode number bit.
+
+
Upper and Lower
---------------
---------------------
The copy_up operation essentially creates a new, identical file and
-moves it over to the old name. The new file may be on a different
-filesystem, so both st_dev and st_ino of the file may change.
+moves it over to the old name. Any open files referring to this inode
+will access the old data.
+
+The new file may be on a different filesystem, so both st_dev and st_ino
+of the real file may change. The values of st_dev and st_ino returned by
+stat(2) on an overlay object are often not the same as the real file
+stat(2) values to prevent the values from changing on copy_up.
-Any open files referring to this inode will access the old data.
+Unless "xino" feature is enabled, when overlay layers are not all on the
+same underlying filesystem, the value of st_dev may be different for two
+non-directory objects in the same overlay filesystem and the value of
+st_ino for directory objects may be non persistent and could change even
+while the overlay filesystem is still mounted.
Unless "inode index" feature is enabled, if a file with multiple hard
links is copied up, then this will "break" the link. Changes will not be
Unless "redirect_dir" feature is enabled, rename(2) on a lower or merged
directory will fail with EXDEV.
+
Changes to underlying filesystems
---------------------------------
if (IS_ERR_OR_NULL(result))
return ERR_PTR(-ESTALE);
+ /*
+ * If no acceptance criteria was specified by caller, a disconnected
+ * dentry is also accepatable. Callers may use this mode to query if
+ * file handle is stale or to get a reference to an inode without
+ * risking the high overhead caused by directory reconnect.
+ */
+ if (!acceptable)
+ return result;
+
if (d_is_dir(result)) {
/*
* This request is for a directory.
case basis with the "nfs_export=on" mount option.
Say N unless you fully understand the consequences.
+
+config OVERLAY_FS_XINO_AUTO
+ bool "Overlayfs: auto enable inode number mapping"
+ default n
+ depends on OVERLAY_FS
+ help
+ If this config option is enabled then overlay filesystems will use
+ unused high bits in undelying filesystem inode numbers to map all
+ inodes to a unified address space. The mapped 64bit inode numbers
+ might not be compatible with applications that expect 32bit inodes.
+
+ If compatibility with applications that expect 32bit inodes is not an
+ issue, then it is safe and recommended to say Y here.
+
+ For more information, see Documentation/filesystems/overlayfs.txt
+
+ If unsure, say N.
return err;
}
-struct ovl_fh *ovl_encode_fh(struct dentry *real, bool is_upper)
+struct ovl_fh *ovl_encode_real_fh(struct dentry *real, bool is_upper)
{
struct ovl_fh *fh;
int fh_type, fh_len, dwords;
* up and a pure upper inode.
*/
if (ovl_can_decode_fh(lower->d_sb)) {
- fh = ovl_encode_fh(lower, false);
+ fh = ovl_encode_real_fh(lower, false);
if (IS_ERR(fh))
return PTR_ERR(fh);
}
const struct ovl_fh *fh;
int err;
- fh = ovl_encode_fh(upper, true);
+ fh = ovl_encode_real_fh(upper, true);
if (IS_ERR(fh))
return PTR_ERR(fh);
goto fail;
/* Encode an upper or lower file handle */
- fh = ovl_encode_fh(enc_lower ? ovl_dentry_lower(dentry) :
- ovl_dentry_upper(dentry), !enc_lower);
+ fh = ovl_encode_real_fh(enc_lower ? ovl_dentry_lower(dentry) :
+ ovl_dentry_upper(dentry), !enc_lower);
err = PTR_ERR(fh);
if (IS_ERR(fh))
goto fail;
return OVL_FILEID;
}
-static int ovl_encode_inode_fh(struct inode *inode, u32 *fid, int *max_len,
- struct inode *parent)
+static int ovl_encode_fh(struct inode *inode, u32 *fid, int *max_len,
+ struct inode *parent)
{
struct dentry *dentry;
int type;
if (d_is_dir(upper ?: lower))
return ERR_PTR(-EIO);
- inode = ovl_get_inode(sb, dget(upper), lower, index, !!lower);
+ inode = ovl_get_inode(sb, dget(upper), lowerpath, index, !!lower);
if (IS_ERR(inode)) {
dput(upper);
return ERR_CAST(inode);
}
- if (index)
- ovl_set_flag(OVL_INDEX, inode);
-
dentry = d_find_any_alias(inode);
if (!dentry) {
dentry = d_alloc_anon(inode->i_sb);
if (!ofs->upper_mnt)
return ERR_PTR(-EACCES);
- upper = ovl_decode_fh(fh, ofs->upper_mnt);
+ upper = ovl_decode_real_fh(fh, ofs->upper_mnt, true);
if (IS_ERR_OR_NULL(upper))
return upper;
struct ovl_path *stack = &origin;
struct dentry *dentry = NULL;
struct dentry *index = NULL;
- struct inode *inode = NULL;
- bool is_deleted = false;
+ struct inode *inode;
int err;
- /* First lookup indexed upper by fh */
+ /* First lookup overlay inode in inode cache by origin fh */
+ err = ovl_check_origin_fh(ofs, fh, false, NULL, &stack);
+ if (err)
+ return ERR_PTR(err);
+
+ if (!d_is_dir(origin.dentry) ||
+ !(origin.dentry->d_flags & DCACHE_DISCONNECTED)) {
+ inode = ovl_lookup_inode(sb, origin.dentry, false);
+ err = PTR_ERR(inode);
+ if (IS_ERR(inode))
+ goto out_err;
+ if (inode) {
+ dentry = d_find_any_alias(inode);
+ iput(inode);
+ if (dentry)
+ goto out;
+ }
+ }
+
+ /* Then lookup indexed upper/whiteout by origin fh */
if (ofs->indexdir) {
index = ovl_get_index_fh(ofs, fh);
err = PTR_ERR(index);
if (IS_ERR(index)) {
- if (err != -ESTALE)
- return ERR_PTR(err);
-
- /* Found a whiteout index - treat as deleted inode */
- is_deleted = true;
index = NULL;
+ goto out_err;
}
}
- /* Then try to get upper dir by index */
+ /* Then try to get a connected upper dir by index */
if (index && d_is_dir(index)) {
struct dentry *upper = ovl_index_upper(ofs, index);
goto out;
}
- /* Then lookup origin by fh */
- err = ovl_check_origin_fh(ofs, fh, NULL, &stack);
- if (err) {
- goto out_err;
- } else if (index) {
- err = ovl_verify_origin(index, origin.dentry, false);
+ /* Otherwise, get a connected non-upper dir or disconnected non-dir */
+ if (d_is_dir(origin.dentry) &&
+ (origin.dentry->d_flags & DCACHE_DISCONNECTED)) {
+ dput(origin.dentry);
+ origin.dentry = NULL;
+ err = ovl_check_origin_fh(ofs, fh, true, NULL, &stack);
if (err)
goto out_err;
- } else if (is_deleted) {
- /* Lookup deleted non-dir by origin inode */
- if (!d_is_dir(origin.dentry))
- inode = ovl_lookup_inode(sb, origin.dentry, false);
- err = -ESTALE;
- if (!inode || atomic_read(&inode->i_count) == 1)
+ }
+ if (index) {
+ err = ovl_verify_origin(index, origin.dentry, false);
+ if (err)
goto out_err;
-
- /* Deleted but still open? */
- index = dget(ovl_i_dentry_upper(inode));
}
dentry = ovl_get_dentry(sb, NULL, &origin, index);
out:
dput(origin.dentry);
dput(index);
- iput(inode);
return dentry;
out_err:
}
const struct export_operations ovl_export_operations = {
- .encode_fh = ovl_encode_inode_fh,
+ .encode_fh = ovl_encode_fh,
.fh_to_dentry = ovl_fh_to_dentry,
.fh_to_parent = ovl_fh_to_parent,
.get_name = ovl_get_name,
#include "overlayfs.h"
-static dev_t ovl_get_pseudo_dev(struct dentry *dentry)
-{
- struct ovl_entry *oe = dentry->d_fsdata;
-
- return oe->lowerstack[0].layer->pseudo_dev;
-}
-
int ovl_setattr(struct dentry *dentry, struct iattr *attr)
{
int err;
return err;
}
+static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat,
+ struct ovl_layer *lower_layer)
+{
+ bool samefs = ovl_same_sb(dentry->d_sb);
+ unsigned int xinobits = ovl_xino_bits(dentry->d_sb);
+
+ if (samefs) {
+ /*
+ * When all layers are on the same fs, all real inode
+ * number are unique, so we use the overlay st_dev,
+ * which is friendly to du -x.
+ */
+ 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.
+ */
+ if (stat->ino >> shift) {
+ pr_warn_ratelimited("overlayfs: 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->dev = dentry->d_sb->s_dev;
+ return 0;
+ }
+ }
+
+ /* The inode could not be mapped to a unified st_ino address space */
+ if (S_ISDIR(dentry->d_inode->i_mode)) {
+ /*
+ * Always use the overlay st_dev for directories, so 'find
+ * -xdev' will scan the entire overlay mount and won't cross the
+ * overlay mount boundaries.
+ *
+ * If not all layers are on the same fs the pair {real st_ino;
+ * overlay st_dev} is not unique, so use the non persistent
+ * overlay st_ino for directories.
+ */
+ stat->dev = dentry->d_sb->s_dev;
+ stat->ino = dentry->d_inode->i_ino;
+ } else if (lower_layer && lower_layer->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
+ * is unique per lower fs. Upper layer uses real st_dev and
+ * lower layers use the unique anonymous bdev assigned to the
+ * lower fs.
+ */
+ stat->dev = lower_layer->fs->pseudo_dev;
+ }
+
+ return 0;
+}
+
int ovl_getattr(const struct path *path, struct kstat *stat,
u32 request_mask, unsigned int flags)
{
const struct cred *old_cred;
bool is_dir = S_ISDIR(dentry->d_inode->i_mode);
bool samefs = ovl_same_sb(dentry->d_sb);
+ struct ovl_layer *lower_layer = NULL;
int err;
type = ovl_path_real(dentry, &realpath);
goto out;
/*
- * For non-dir or same fs, we use st_ino of the copy up origin, if we
- * know it. This guaranties constant st_dev/st_ino across copy up.
+ * For non-dir or same fs, we use st_ino of the copy up origin.
+ * This guaranties constant st_dev/st_ino across copy up.
+ * With xino feature and non-samefs, we use st_ino of the copy up
+ * origin masked with high bits that represent the layer id.
*
- * If filesystem supports NFS export ops, this also guaranties
+ * If lower filesystem supports NFS file handles, this also guaranties
* persistent st_ino across mount cycle.
*/
- if (!is_dir || samefs) {
- if (OVL_TYPE_ORIGIN(type)) {
+ if (!is_dir || samefs || ovl_xino_bits(dentry->d_sb)) {
+ if (!OVL_TYPE_UPPER(type)) {
+ lower_layer = ovl_layer_lower(dentry);
+ } else if (OVL_TYPE_ORIGIN(type)) {
struct kstat lowerstat;
u32 lowermask = STATX_INO | (!is_dir ? STATX_NLINK : 0);
*/
if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) ||
(!ovl_verify_lower(dentry->d_sb) &&
- (is_dir || lowerstat.nlink == 1)))
+ (is_dir || lowerstat.nlink == 1))) {
stat->ino = lowerstat.ino;
-
- if (samefs)
- WARN_ON_ONCE(stat->dev != lowerstat.dev);
- else
- stat->dev = ovl_get_pseudo_dev(dentry);
- }
- if (samefs) {
- /*
- * When all layers are on the same fs, all real inode
- * number are unique, so we use the overlay st_dev,
- * which is friendly to du -x.
- */
- stat->dev = dentry->d_sb->s_dev;
- } else if (!OVL_TYPE_UPPER(type)) {
- /*
- * For non-samefs setup, to make sure that st_dev/st_ino
- * pair is unique across the system, we use a unique
- * anonymous st_dev for lower layer inode.
- */
- stat->dev = ovl_get_pseudo_dev(dentry);
+ lower_layer = ovl_layer_lower(dentry);
+ }
}
- } else {
- /*
- * Always use the overlay st_dev for directories, so 'find
- * -xdev' will scan the entire overlay mount and won't cross the
- * overlay mount boundaries.
- *
- * If not all layers are on the same fs the pair {real st_ino;
- * overlay st_dev} is not unique, so use the non persistent
- * overlay st_ino for directories.
- */
- stat->dev = dentry->d_sb->s_dev;
- stat->ino = dentry->d_inode->i_ino;
}
+ err = ovl_map_dev_ino(dentry, stat, lower_layer);
+ if (err)
+ goto out;
+
/*
* It's probably not worth it to count subdirs to get the
* correct link count. nlink=1 seems to pacify 'find' and
int ovl_update_time(struct inode *inode, struct timespec *ts, int flags)
{
- struct dentry *alias;
- struct path upperpath;
-
- if (!(flags & S_ATIME))
- return 0;
-
- alias = d_find_any_alias(inode);
- if (!alias)
- return 0;
-
- ovl_path_upper(alias, &upperpath);
- if (upperpath.dentry) {
- touch_atime(&upperpath);
- inode->i_atime = d_inode(upperpath.dentry)->i_atime;
+ if (flags & S_ATIME) {
+ struct ovl_fs *ofs = inode->i_sb->s_fs_info;
+ struct path upperpath = {
+ .mnt = ofs->upper_mnt,
+ .dentry = ovl_upperdentry_dereference(OVL_I(inode)),
+ };
+
+ if (upperpath.dentry) {
+ touch_atime(&upperpath);
+ inode->i_atime = d_inode(upperpath.dentry)->i_atime;
+ }
}
-
- dput(alias);
-
return 0;
}
#endif
}
-static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev)
+static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev,
+ unsigned long ino, int fsid)
{
- inode->i_ino = get_next_ino();
+ int xinobits = ovl_xino_bits(inode->i_sb);
+
+ /*
+ * When NFS export is enabled and d_ino is consistent with st_ino
+ * (samefs or i_ino has enough bits to encode layer), set the same
+ * value used for d_ino to i_ino, because nfsd readdirplus compares
+ * d_ino values to i_ino values of child entries. 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().
+ */
+ if (inode->i_sb->s_export_op &&
+ (ovl_same_sb(inode->i_sb) || xinobits)) {
+ 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_mode = mode;
inode->i_flags |= S_NOCMTIME;
#ifdef CONFIG_FS_POSIX_ACL
inode = new_inode(sb);
if (inode)
- ovl_fill_inode(inode, mode, rdev);
+ ovl_fill_inode(inode, mode, rdev, 0, 0);
return inode;
}
}
struct inode *ovl_get_inode(struct super_block *sb, struct dentry *upperdentry,
- struct dentry *lowerdentry, struct dentry *index,
+ struct ovl_path *lowerpath, struct dentry *index,
unsigned int numlower)
{
struct inode *realinode = upperdentry ? d_inode(upperdentry) : NULL;
struct inode *inode;
+ struct dentry *lowerdentry = lowerpath ? lowerpath->dentry : NULL;
bool bylower = ovl_hash_bylower(sb, upperdentry, lowerdentry, index);
+ int fsid = bylower ? lowerpath->layer->fsid : 0;
bool is_dir;
+ unsigned long ino = 0;
if (!realinode)
realinode = d_inode(lowerdentry);
if (!is_dir)
nlink = ovl_get_nlink(lowerdentry, upperdentry, nlink);
set_nlink(inode, nlink);
+ ino = key->i_ino;
} else {
/* Lower hardlink that will be broken on copy up */
inode = new_inode(sb);
if (!inode)
goto out_nomem;
}
- ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev);
+ ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev, ino, fsid);
ovl_inode_init(inode, upperdentry, lowerdentry);
if (upperdentry && ovl_is_impuredir(upperdentry))
ovl_set_flag(OVL_IMPURE, inode);
+ if (index)
+ ovl_set_flag(OVL_INDEX, inode);
+
/* Check for non-merge dir that may have whiteouts */
if (is_dir) {
if (((upperdentry && lowerdentry) || numlower > 1) ||
if (s == next)
goto invalid;
}
+ /*
+ * One of the ancestor path elements in an absolute path
+ * lookup in ovl_lookup_layer() could have been opaque and
+ * that will stop further lookup in lower layers (d->stop=true)
+ * But we have found an absolute redirect in decendant path
+ * element and that should force continue lookup in lower
+ * layers (reset d->stop).
+ */
+ d->stop = false;
} else {
if (strchr(buf, '/') != NULL)
goto invalid;
goto out;
}
-struct dentry *ovl_decode_fh(struct ovl_fh *fh, struct vfsmount *mnt)
+struct dentry *ovl_decode_real_fh(struct ovl_fh *fh, struct vfsmount *mnt,
+ bool connected)
{
struct dentry *real;
int bytes;
bytes = (fh->len - offsetof(struct ovl_fh, fid));
real = exportfs_decode_fh(mnt, (struct fid *)fh->fid,
bytes >> 2, (int)fh->type,
- ovl_acceptable, mnt);
+ connected ? ovl_acceptable : NULL, mnt);
if (IS_ERR(real)) {
/*
* Treat stale file handle to lower file as "origin unknown".
{
struct dentry *this;
int err;
+ bool last_element = !post[0];
this = lookup_one_len_unlocked(name, base, namelen);
if (IS_ERR(this)) {
d->stop = true;
if (d->is_dir)
goto put_and_out;
+
+ /*
+ * NB: handle failure to lookup non-last element when non-dir
+ * redirects become possible
+ */
+ WARN_ON(!last_element);
goto out;
}
- d->is_dir = true;
- if (!d->last && ovl_is_opaquedir(this)) {
- d->stop = d->opaque = true;
+ if (last_element)
+ d->is_dir = true;
+ if (d->last)
+ goto out;
+
+ if (ovl_is_opaquedir(this)) {
+ d->stop = true;
+ if (last_element)
+ d->opaque = true;
goto out;
}
err = ovl_check_redirect(this, d, prelen, post);
}
-int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh,
+int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
struct dentry *upperdentry, struct ovl_path **stackp)
{
struct dentry *origin = NULL;
int i;
for (i = 0; i < ofs->numlower; i++) {
- origin = ovl_decode_fh(fh, ofs->lower_layers[i].mnt);
+ origin = ovl_decode_real_fh(fh, ofs->lower_layers[i].mnt,
+ connected);
if (origin)
break;
}
if (IS_ERR_OR_NULL(fh))
return PTR_ERR(fh);
- err = ovl_check_origin_fh(ofs, fh, upperdentry, stackp);
+ err = ovl_check_origin_fh(ofs, fh, false, upperdentry, stackp);
kfree(fh);
if (err) {
struct ovl_fh *fh;
int err;
- fh = ovl_encode_fh(real, is_upper);
+ fh = ovl_encode_real_fh(real, is_upper);
err = PTR_ERR(fh);
if (IS_ERR(fh))
goto fail;
if (IS_ERR_OR_NULL(fh))
return ERR_CAST(fh);
- upper = ovl_decode_fh(fh, ofs->upper_mnt);
+ upper = ovl_decode_real_fh(fh, ofs->upper_mnt, true);
kfree(fh);
if (IS_ERR_OR_NULL(upper))
/* Check if non-dir index is orphan and don't warn before cleaning it */
if (!d_is_dir(index) && d_inode(index)->i_nlink == 1) {
- err = ovl_check_origin_fh(ofs, fh, index, &stack);
+ err = ovl_check_origin_fh(ofs, fh, false, index, &stack);
if (err)
goto fail;
struct ovl_fh *fh;
int err;
- fh = ovl_encode_fh(origin, false);
+ fh = ovl_encode_real_fh(origin, false);
if (IS_ERR(fh))
return PTR_ERR(fh);
.is_dir = false,
.opaque = false,
.stop = false,
- .last = !poe->numlower,
+ .last = ofs->config.redirect_follow ? false : !poe->numlower,
.redirect = NULL,
};
for (i = 0; !d.stop && i < poe->numlower; i++) {
struct ovl_path lower = poe->lowerstack[i];
- d.last = i == poe->numlower - 1;
+ if (!ofs->config.redirect_follow)
+ d.last = i == poe->numlower - 1;
+ else
+ d.last = lower.layer->idx == roe->numlower;
+
err = ovl_lookup_layer(lower.dentry, &d, &this);
if (err)
goto out_put;
upperdentry = dget(index);
if (upperdentry || ctr) {
- if (ctr)
- origin = stack[0].dentry;
- inode = ovl_get_inode(dentry->d_sb, upperdentry, origin, index,
+ inode = ovl_get_inode(dentry->d_sb, upperdentry, stack, index,
ctr);
err = PTR_ERR(inode);
if (IS_ERR(inode))
goto out_free_oe;
+ /*
+ * NB: handle redirected hard links when non-dir redirects
+ * become possible
+ */
+ WARN_ON(OVL_I(inode)->redirect);
OVL_I(inode)->redirect = upperredirect;
- if (index)
- ovl_set_flag(OVL_INDEX, inode);
}
revert_creds(old_cred);
struct dentry *ovl_workdir(struct dentry *dentry);
const struct cred *ovl_override_creds(struct super_block *sb);
struct super_block *ovl_same_sb(struct super_block *sb);
-bool ovl_can_decode_fh(struct super_block *sb);
+int ovl_can_decode_fh(struct super_block *sb);
struct dentry *ovl_indexdir(struct super_block *sb);
bool ovl_index_all(struct super_block *sb);
bool ovl_verify_lower(struct super_block *sb);
enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
struct dentry *ovl_dentry_upper(struct dentry *dentry);
struct dentry *ovl_dentry_lower(struct dentry *dentry);
+struct ovl_layer *ovl_layer_lower(struct dentry *dentry);
struct dentry *ovl_dentry_real(struct dentry *dentry);
struct dentry *ovl_i_dentry_upper(struct inode *inode);
struct inode *ovl_inode_upper(struct inode *inode);
return ovl_check_dir_xattr(dentry, OVL_XATTR_IMPURE);
}
+static inline unsigned int ovl_xino_bits(struct super_block *sb)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+
+ return ofs->xino_bits;
+}
+
/* namei.c */
int ovl_check_fh_len(struct ovl_fh *fh, int fh_len);
-struct dentry *ovl_decode_fh(struct ovl_fh *fh, struct vfsmount *mnt);
-int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh,
+struct dentry *ovl_decode_real_fh(struct ovl_fh *fh, struct vfsmount *mnt,
+ bool connected);
+int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
struct dentry *upperdentry, struct ovl_path **stackp);
int ovl_verify_set_fh(struct dentry *dentry, const char *name,
struct dentry *real, bool is_upper, bool set);
struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real,
bool is_upper);
struct inode *ovl_get_inode(struct super_block *sb, struct dentry *upperdentry,
- struct dentry *lowerdentry, struct dentry *index,
+ struct ovl_path *lowerpath, struct dentry *index,
unsigned int numlower);
static inline void ovl_copyattr(struct inode *from, struct inode *to)
{
int ovl_copy_up_flags(struct dentry *dentry, int flags);
int ovl_copy_xattr(struct dentry *old, struct dentry *new);
int ovl_set_attr(struct dentry *upper, struct kstat *stat);
-struct ovl_fh *ovl_encode_fh(struct dentry *real, bool is_upper);
+struct ovl_fh *ovl_encode_real_fh(struct dentry *real, bool is_upper);
int ovl_set_origin(struct dentry *dentry, struct dentry *lower,
struct dentry *upper);
const char *redirect_mode;
bool index;
bool nfs_export;
+ int xino;
+};
+
+struct ovl_sb {
+ struct super_block *sb;
+ dev_t pseudo_dev;
};
struct ovl_layer {
struct vfsmount *mnt;
- dev_t pseudo_dev;
- /* Index of this layer in fs root (upper == 0) */
+ struct ovl_sb *fs;
+ /* Index of this layer in fs root (upper idx == 0) */
int idx;
+ /* One fsid per unique underlying sb (upper fsid == 0) */
+ int fsid;
};
struct ovl_path {
/* private information held for overlayfs's superblock */
struct ovl_fs {
struct vfsmount *upper_mnt;
- unsigned numlower;
+ unsigned int numlower;
+ /* Number of unique lower sb that differ from upper sb */
+ unsigned int numlowerfs;
struct ovl_layer *lower_layers;
+ struct ovl_sb *lower_fs;
/* workbasedir is the path at workdir= mount option */
struct dentry *workbasedir;
/* workdir is the 'work' directory under workbasedir */
const struct cred *creator_cred;
bool tmpfile;
bool noxattr;
- /* sb common to all layers */
- struct super_block *same_sb;
/* Did we take the inuse lock? */
bool upperdir_locked;
bool workdir_locked;
+ /* Inode numbers in all layers do not use the high xino_bits */
+ unsigned int xino_bits;
};
/* private information held for every overlayfs dentry */
if (!rdd->dentry)
return false;
+ /* Always recalc d_ino when remapping lower inode numbers */
+ if (ovl_xino_bits(rdd->dentry->d_sb))
+ return true;
+
/* Always recalc d_ino for parent */
if (strcmp(p->name, "..") == 0)
return true;
return cache;
}
+/* Map inode number to lower fs unique range */
+static u64 ovl_remap_lower_ino(u64 ino, int xinobits, int fsid,
+ const char *name, int namelen)
+{
+ if (ino >> (64 - xinobits)) {
+ pr_warn_ratelimited("overlayfs: d_ino too big (%.*s, ino=%llu, xinobits=%d)\n",
+ namelen, name, ino, xinobits);
+ return ino;
+ }
+
+ return ino | ((u64)fsid) << (64 - xinobits);
+}
+
/*
* Set d_ino for upper entries. Non-upper entries should always report
* the uppermost real inode ino and should not call this function.
struct dentry *this = NULL;
enum ovl_path_type type;
u64 ino = p->real_ino;
+ int xinobits = ovl_xino_bits(dir->d_sb);
int err = 0;
- if (!ovl_same_sb(dir->d_sb))
+ if (!ovl_same_sb(dir->d_sb) && !xinobits)
goto out;
if (p->name[0] == '.') {
WARN_ON_ONCE(dir->d_sb->s_dev != stat.dev);
ino = stat.ino;
+ } else if (xinobits && !OVL_TYPE_UPPER(type)) {
+ ino = ovl_remap_lower_ino(ino, xinobits,
+ ovl_layer_lower(this)->fsid,
+ p->name, p->len);
}
out:
struct ovl_dir_cache *cache;
struct dir_context ctx;
u64 parent_ino;
+ int fsid;
+ int xinobits;
};
static int ovl_fill_real(struct dir_context *ctx, const char *name,
container_of(ctx, struct ovl_readdir_translate, ctx);
struct dir_context *orig_ctx = rdt->orig_ctx;
- if (rdt->parent_ino && strcmp(name, "..") == 0)
+ if (rdt->parent_ino && strcmp(name, "..") == 0) {
ino = rdt->parent_ino;
- else if (rdt->cache) {
+ } else if (rdt->cache) {
struct ovl_cache_entry *p;
p = ovl_cache_entry_find(&rdt->cache->root, name, namelen);
if (p)
ino = p->ino;
+ } else if (rdt->xinobits) {
+ ino = ovl_remap_lower_ino(ino, rdt->xinobits, rdt->fsid,
+ name, namelen);
}
return orig_ctx->actor(orig_ctx, name, namelen, offset, ino, d_type);
int err;
struct ovl_dir_file *od = file->private_data;
struct dentry *dir = file->f_path.dentry;
+ struct ovl_layer *lower_layer = ovl_layer_lower(dir);
struct ovl_readdir_translate rdt = {
.ctx.actor = ovl_fill_real,
.orig_ctx = ctx,
+ .xinobits = ovl_xino_bits(dir->d_sb),
};
+ if (rdt.xinobits && lower_layer)
+ rdt.fsid = lower_layer->fsid;
+
if (OVL_TYPE_MERGE(ovl_path_type(dir->d_parent))) {
struct kstat stat;
struct path statpath = file->f_path;
* dir is impure then need to adjust d_ino for copied up
* entries.
*/
- if (ovl_same_sb(dentry->d_sb) &&
- (ovl_test_flag(OVL_IMPURE, d_inode(dentry)) ||
- OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent)))) {
+ if (ovl_xino_bits(dentry->d_sb) ||
+ (ovl_same_sb(dentry->d_sb) &&
+ (ovl_test_flag(OVL_IMPURE, d_inode(dentry)) ||
+ OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent))))) {
return ovl_iterate_real(file, ctx);
}
return iterate_dir(od->realfile, ctx);
#include <linux/statfs.h>
#include <linux/seq_file.h>
#include <linux/posix_acl_xattr.h>
+#include <linux/exportfs.h>
#include "overlayfs.h"
MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
MODULE_PARM_DESC(ovl_nfs_export_def,
"Default to on or off for the NFS export feature");
+static bool ovl_xino_auto_def = IS_ENABLED(CONFIG_OVERLAY_FS_XINO_AUTO);
+module_param_named(xino_auto, ovl_xino_auto_def, bool, 0644);
+MODULE_PARM_DESC(ovl_xino_auto_def,
+ "Auto enable xino feature");
+
static void ovl_entry_stack_free(struct ovl_entry *oe)
{
unsigned int i;
if (ofs->upperdir_locked)
ovl_inuse_unlock(ofs->upper_mnt->mnt_root);
mntput(ofs->upper_mnt);
- for (i = 0; i < ofs->numlower; i++) {
+ for (i = 0; i < ofs->numlower; i++)
mntput(ofs->lower_layers[i].mnt);
- free_anon_bdev(ofs->lower_layers[i].pseudo_dev);
- }
+ for (i = 0; i < ofs->numlowerfs; i++)
+ free_anon_bdev(ofs->lower_fs[i].pseudo_dev);
kfree(ofs->lower_layers);
+ kfree(ofs->lower_fs);
kfree(ofs->config.lowerdir);
kfree(ofs->config.upperdir);
return ovl_redirect_dir_def ? "on" : "off";
}
+enum {
+ OVL_XINO_OFF,
+ OVL_XINO_AUTO,
+ OVL_XINO_ON,
+};
+
+static const char * const ovl_xino_str[] = {
+ "off",
+ "auto",
+ "on",
+};
+
+static inline int ovl_xino_def(void)
+{
+ return ovl_xino_auto_def ? OVL_XINO_AUTO : OVL_XINO_OFF;
+}
+
/**
* ovl_show_options
*
if (ofs->config.nfs_export != ovl_nfs_export_def)
seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ?
"on" : "off");
+ if (ofs->config.xino != ovl_xino_def())
+ seq_printf(m, ",xino=%s", ovl_xino_str[ofs->config.xino]);
return 0;
}
OPT_INDEX_OFF,
OPT_NFS_EXPORT_ON,
OPT_NFS_EXPORT_OFF,
+ OPT_XINO_ON,
+ OPT_XINO_OFF,
+ OPT_XINO_AUTO,
OPT_ERR,
};
{OPT_INDEX_OFF, "index=off"},
{OPT_NFS_EXPORT_ON, "nfs_export=on"},
{OPT_NFS_EXPORT_OFF, "nfs_export=off"},
+ {OPT_XINO_ON, "xino=on"},
+ {OPT_XINO_OFF, "xino=off"},
+ {OPT_XINO_AUTO, "xino=auto"},
{OPT_ERR, NULL}
};
config->nfs_export = false;
break;
+ case OPT_XINO_ON:
+ config->xino = OVL_XINO_ON;
+ break;
+
+ case OPT_XINO_OFF:
+ config->xino = OVL_XINO_OFF;
+ break;
+
+ case OPT_XINO_AUTO:
+ config->xino = OVL_XINO_AUTO;
+ break;
+
default:
pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p);
return -EINVAL;
static int ovl_lower_dir(const char *name, struct path *path,
struct ovl_fs *ofs, int *stack_depth, bool *remote)
{
+ int fh_type;
int err;
err = ovl_mount_dir_noesc(name, path);
* The inodes index feature and NFS export need to encode and decode
* file handles, so they require that all layers support them.
*/
+ fh_type = ovl_can_decode_fh(path->dentry->d_sb);
if ((ofs->config.nfs_export ||
- (ofs->config.index && ofs->config.upperdir)) &&
- !ovl_can_decode_fh(path->dentry->d_sb)) {
+ (ofs->config.index && ofs->config.upperdir)) && !fh_type) {
ofs->config.index = false;
ofs->config.nfs_export = false;
pr_warn("overlayfs: fs on '%s' does not support file handles, falling back to index=off,nfs_export=off.\n",
name);
}
+ /* Check if lower fs has 32bit inode numbers */
+ if (fh_type != FILEID_INO32_GEN)
+ ofs->xino_bits = 0;
+
return 0;
out_put:
{
struct vfsmount *mnt = ofs->upper_mnt;
struct dentry *temp;
+ int fh_type;
int err;
err = mnt_want_write(mnt);
}
/* Check if upper/work fs supports file handles */
- if (ofs->config.index &&
- !ovl_can_decode_fh(ofs->workdir->d_sb)) {
+ fh_type = ovl_can_decode_fh(ofs->workdir->d_sb);
+ if (ofs->config.index && !fh_type) {
ofs->config.index = false;
pr_warn("overlayfs: upper fs does not support file handles, falling back to index=off.\n");
}
+ /* Check if upper fs has 32bit inode numbers */
+ if (fh_type != FILEID_INO32_GEN)
+ ofs->xino_bits = 0;
+
/* NFS export of r/w mount depends on index */
if (ofs->config.nfs_export && !ofs->config.index) {
pr_warn("overlayfs: NFS export requires \"index=on\", falling back to nfs_export=off.\n");
return err;
}
+/* Get a unique fsid for the layer */
+static int ovl_get_fsid(struct ovl_fs *ofs, struct super_block *sb)
+{
+ unsigned int i;
+ dev_t dev;
+ int err;
+
+ /* 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;
+ }
+
+ err = get_anon_bdev(&dev);
+ if (err) {
+ pr_err("overlayfs: failed to get anonymous bdev for lowerpath\n");
+ return err;
+ }
+
+ ofs->lower_fs[ofs->numlowerfs].sb = sb;
+ ofs->lower_fs[ofs->numlowerfs].pseudo_dev = dev;
+ ofs->numlowerfs++;
+
+ return ofs->numlowerfs;
+}
+
static int ovl_get_lower_layers(struct ovl_fs *ofs, struct path *stack,
unsigned int numlower)
{
GFP_KERNEL);
if (ofs->lower_layers == NULL)
goto out;
+
+ ofs->lower_fs = kcalloc(numlower, sizeof(struct ovl_sb),
+ GFP_KERNEL);
+ if (ofs->lower_fs == NULL)
+ goto out;
+
for (i = 0; i < numlower; i++) {
struct vfsmount *mnt;
- dev_t dev;
+ int fsid;
- err = get_anon_bdev(&dev);
- if (err) {
- pr_err("overlayfs: failed to get anonymous bdev for lowerpath\n");
+ err = fsid = ovl_get_fsid(ofs, stack[i].mnt->mnt_sb);
+ if (err < 0)
goto out;
- }
mnt = clone_private_mount(&stack[i]);
err = PTR_ERR(mnt);
if (IS_ERR(mnt)) {
pr_err("overlayfs: failed to clone lowerpath\n");
- free_anon_bdev(dev);
goto out;
}
+
/*
* Make lower layers R/O. That way fchmod/fchown on lower file
* will fail instead of modifying lower fs.
mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME;
ofs->lower_layers[ofs->numlower].mnt = mnt;
- ofs->lower_layers[ofs->numlower].pseudo_dev = dev;
ofs->lower_layers[ofs->numlower].idx = i + 1;
+ ofs->lower_layers[ofs->numlower].fsid = fsid;
+ if (fsid) {
+ ofs->lower_layers[ofs->numlower].fs =
+ &ofs->lower_fs[fsid - 1];
+ }
ofs->numlower++;
+ }
+
+ /*
+ * When all layers on same fs, overlay can use real inode numbers.
+ * With mount option "xino=on", mounter declares that there are enough
+ * 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.
+ */
+ if (!ofs->numlowerfs || (ofs->numlowerfs == 1 && !ofs->upper_mnt)) {
+ ofs->xino_bits = 0;
+ ofs->config.xino = OVL_XINO_OFF;
+ } else if (ofs->config.xino == OVL_XINO_ON && !ofs->xino_bits) {
+ /*
+ * 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.
+ */
+ BUILD_BUG_ON(ilog2(OVL_MAX_STACK) > 31);
+ ofs->xino_bits = ilog2(ofs->numlowerfs) + 1;
+ }
- /* Check if all lower layers are on same sb */
- if (i == 0)
- ofs->same_sb = mnt->mnt_sb;
- else if (ofs->same_sb != mnt->mnt_sb)
- ofs->same_sb = NULL;
+ if (ofs->xino_bits) {
+ pr_info("overlayfs: \"xino\" feature enabled using %d upper inode bits.\n",
+ ofs->xino_bits);
}
+
err = 0;
out:
return err;
ofs->config.index = ovl_index_def;
ofs->config.nfs_export = ovl_nfs_export_def;
+ ofs->config.xino = ovl_xino_def();
err = ovl_parse_opt((char *) data, &ofs->config);
if (err)
goto out_err;
sb->s_stack_depth = 0;
sb->s_maxbytes = MAX_LFS_FILESIZE;
+ /* Assume underlaying fs uses 32bit inodes unless proven otherwise */
+ if (ofs->config.xino != OVL_XINO_OFF)
+ ofs->xino_bits = BITS_PER_LONG - 32;
+
if (ofs->config.upperdir) {
if (!ofs->config.workdir) {
pr_err("overlayfs: missing 'workdir'\n");
/* If the upper fs is nonexistent, we mark overlayfs r/o too */
if (!ofs->upper_mnt)
sb->s_flags |= SB_RDONLY;
- else if (ofs->upper_mnt->mnt_sb != ofs->same_sb)
- ofs->same_sb = NULL;
if (!(ovl_force_readonly(ofs)) && ofs->config.index) {
err = ovl_get_indexdir(ofs, oe, &upperpath);
{
struct ovl_fs *ofs = sb->s_fs_info;
- return ofs->same_sb;
+ if (!ofs->numlowerfs)
+ return ofs->upper_mnt->mnt_sb;
+ else if (ofs->numlowerfs == 1 && !ofs->upper_mnt)
+ return ofs->lower_fs[0].sb;
+ else
+ return NULL;
}
-bool ovl_can_decode_fh(struct super_block *sb)
+/*
+ * Check if underlying fs supports file handles and try to determine encoding
+ * type, in order to deduce maximum inode number used by fs.
+ *
+ * Return 0 if file handles are not supported.
+ * Return 1 (FILEID_INO32_GEN) if fs uses the default 32bit inode encoding.
+ * Return -1 if fs uses a non default encoding with unknown inode size.
+ */
+int ovl_can_decode_fh(struct super_block *sb)
{
- return (sb->s_export_op && sb->s_export_op->fh_to_dentry &&
- !uuid_is_null(&sb->s_uuid));
+ if (!sb->s_export_op || !sb->s_export_op->fh_to_dentry ||
+ uuid_is_null(&sb->s_uuid))
+ return 0;
+
+ return sb->s_export_op->encode_fh ? -1 : FILEID_INO32_GEN;
}
struct dentry *ovl_indexdir(struct super_block *sb)
return oe->numlower ? oe->lowerstack[0].dentry : NULL;
}
+struct ovl_layer *ovl_layer_lower(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ return oe->numlower ? oe->lowerstack[0].layer : NULL;
+}
+
struct dentry *ovl_dentry_real(struct dentry *dentry)
{
return ovl_dentry_upper(dentry) ?: ovl_dentry_lower(dentry);
void ovl_inode_init(struct inode *inode, struct dentry *upperdentry,
struct dentry *lowerdentry)
{
+ struct inode *realinode = d_inode(upperdentry ?: lowerdentry);
+
if (upperdentry)
OVL_I(inode)->__upperdentry = upperdentry;
if (lowerdentry)
OVL_I(inode)->lower = igrab(d_inode(lowerdentry));
- ovl_copyattr(d_inode(upperdentry ?: lowerdentry), inode);
+ ovl_copyattr(realinode, inode);
+ if (!inode->i_ino)
+ inode->i_ino = realinode->i_ino;
}
void ovl_inode_update(struct inode *inode, struct dentry *upperdentry)
smp_wmb();
OVL_I(inode)->__upperdentry = upperdentry;
if (inode_unhashed(inode)) {
+ if (!inode->i_ino)
+ inode->i_ino = upperinode->i_ino;
inode->i_private = upperinode;
__insert_inode_hash(inode, (unsigned long) upperinode);
}
git.samba.org / sfrench / cifs-2.6.git / commitdiff