diff options
Diffstat (limited to 'fs/overlayfs/export.c')
| -rw-r--r-- | fs/overlayfs/export.c | 892 |
1 files changed, 892 insertions, 0 deletions
diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c new file mode 100644 index 000000000..26b782c53 --- /dev/null +++ b/fs/overlayfs/export.c @@ -0,0 +1,892 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Overlayfs NFS export support. + * + * Amir Goldstein <amir73il@gmail.com> + * + * Copyright (C) 2017-2018 CTERA Networks. All Rights Reserved. + */ + +#include <linux/fs.h> +#include <linux/cred.h> +#include <linux/mount.h> +#include <linux/namei.h> +#include <linux/xattr.h> +#include <linux/exportfs.h> +#include <linux/ratelimit.h> +#include "overlayfs.h" + +static int ovl_encode_maybe_copy_up(struct dentry *dentry) +{ + int err; + + if (ovl_dentry_upper(dentry)) + return 0; + + err = ovl_want_write(dentry); + if (!err) { + err = ovl_copy_up(dentry); + ovl_drop_write(dentry); + } + + if (err) { + pr_warn_ratelimited("failed to copy up on encode (%pd2, err=%i)\n", + dentry, err); + } + + return err; +} + +/* + * Before encoding a non-upper directory file handle from real layer N, we need + * to check if it will be possible to reconnect an overlay dentry from the real + * lower decoded dentry. This is done by following the overlay ancestry up to a + * "layer N connected" ancestor and verifying that all parents along the way are + * "layer N connectable". If an ancestor that is NOT "layer N connectable" is + * found, we need to copy up an ancestor, which is "layer N connectable", thus + * making that ancestor "layer N connected". For example: + * + * layer 1: /a + * layer 2: /a/b/c + * + * The overlay dentry /a is NOT "layer 2 connectable", because if dir /a is + * copied up and renamed, upper dir /a will be indexed by lower dir /a from + * layer 1. The dir /a from layer 2 will never be indexed, so the algorithm (*) + * in ovl_lookup_real_ancestor() will not be able to lookup a connected overlay + * dentry from the connected lower dentry /a/b/c. + * + * To avoid this problem on decode time, we need to copy up an ancestor of + * /a/b/c, which is "layer 2 connectable", on encode time. That ancestor is + * /a/b. After copy up (and index) of /a/b, it will become "layer 2 connected" + * and when the time comes to decode the file handle from lower dentry /a/b/c, + * ovl_lookup_real_ancestor() will find the indexed ancestor /a/b and decoding + * a connected overlay dentry will be accomplished. + * + * (*) the algorithm in ovl_lookup_real_ancestor() can be improved to lookup an + * entry /a in the lower layers above layer N and find the indexed dir /a from + * layer 1. If that improvement is made, then the check for "layer N connected" + * will need to verify there are no redirects in lower layers above N. In the + * example above, /a will be "layer 2 connectable". However, if layer 2 dir /a + * is a target of a layer 1 redirect, then /a will NOT be "layer 2 connectable": + * + * layer 1: /A (redirect = /a) + * layer 2: /a/b/c + */ + +/* Return the lowest layer for encoding a connectable file handle */ +static int ovl_connectable_layer(struct dentry *dentry) +{ + struct ovl_entry *oe = OVL_E(dentry); + + /* We can get overlay root from root of any layer */ + if (dentry == dentry->d_sb->s_root) + return ovl_numlower(oe); + + /* + * If it's an unindexed merge dir, then it's not connectable with any + * lower layer + */ + if (ovl_dentry_upper(dentry) && + !ovl_test_flag(OVL_INDEX, d_inode(dentry))) + return 0; + + /* We can get upper/overlay path from indexed/lower dentry */ + return ovl_lowerstack(oe)->layer->idx; +} + +/* + * @dentry is "connected" if all ancestors up to root or a "connected" ancestor + * have the same uppermost lower layer as the origin's layer. We may need to + * copy up a "connectable" ancestor to make it "connected". A "connected" dentry + * cannot become non "connected", so cache positive result in dentry flags. + * + * Return the connected origin layer or < 0 on error. + */ +static int ovl_connect_layer(struct dentry *dentry) +{ + struct dentry *next, *parent = NULL; + struct ovl_entry *oe = OVL_E(dentry); + int origin_layer; + int err = 0; + + if (WARN_ON(dentry == dentry->d_sb->s_root) || + WARN_ON(!ovl_dentry_lower(dentry))) + return -EIO; + + origin_layer = ovl_lowerstack(oe)->layer->idx; + if (ovl_dentry_test_flag(OVL_E_CONNECTED, dentry)) + return origin_layer; + + /* Find the topmost origin layer connectable ancestor of @dentry */ + next = dget(dentry); + for (;;) { + parent = dget_parent(next); + if (WARN_ON(parent == next)) { + err = -EIO; + break; + } + + /* + * If @parent is not origin layer connectable, then copy up + * @next which is origin layer connectable and we are done. + */ + if (ovl_connectable_layer(parent) < origin_layer) { + err = ovl_encode_maybe_copy_up(next); + break; + } + + /* If @parent is connected or indexed we are done */ + if (ovl_dentry_test_flag(OVL_E_CONNECTED, parent) || + ovl_test_flag(OVL_INDEX, d_inode(parent))) + break; + + dput(next); + next = parent; + } + + dput(parent); + dput(next); + + if (!err) + ovl_dentry_set_flag(OVL_E_CONNECTED, dentry); + + return err ?: origin_layer; +} + +/* + * We only need to encode origin if there is a chance that the same object was + * encoded pre copy up and then we need to stay consistent with the same + * encoding also after copy up. If non-pure upper is not indexed, then it was + * copied up before NFS export was enabled. In that case we don't need to worry + * about staying consistent with pre copy up encoding and we encode an upper + * file handle. Overlay root dentry is a private case of non-indexed upper. + * + * The following table summarizes the different file handle encodings used for + * different overlay object types: + * + * Object type | Encoding + * -------------------------------- + * Pure upper | U + * Non-indexed upper | U + * Indexed upper | L (*) + * Non-upper | L (*) + * + * U = upper file handle + * L = lower file handle + * + * (*) Decoding a connected overlay dir from real lower dentry is not always + * possible when there are redirects in lower layers and non-indexed merge dirs. + * To mitigate those case, we may copy up the lower dir ancestor before encode + * of a decodable file handle for non-upper dir. + * + * Return 0 for upper file handle, > 0 for lower file handle or < 0 on error. + */ +static int ovl_check_encode_origin(struct dentry *dentry) +{ + struct ovl_fs *ofs = OVL_FS(dentry->d_sb); + bool decodable = ofs->config.nfs_export; + + /* Lower file handle for non-upper non-decodable */ + if (!ovl_dentry_upper(dentry) && !decodable) + return 1; + + /* Upper file handle for pure upper */ + if (!ovl_dentry_lower(dentry)) + return 0; + + /* + * Root is never indexed, so if there's an upper layer, encode upper for + * root. + */ + if (dentry == dentry->d_sb->s_root) + return 0; + + /* + * Upper decodable file handle for non-indexed upper. + */ + if (ovl_dentry_upper(dentry) && decodable && + !ovl_test_flag(OVL_INDEX, d_inode(dentry))) + return 0; + + /* + * Decoding a merge dir, whose origin's ancestor is under a redirected + * lower dir or under a non-indexed upper is not always possible. + * ovl_connect_layer() will try to make origin's layer "connected" by + * copying up a "connectable" ancestor. + */ + if (d_is_dir(dentry) && ovl_upper_mnt(ofs) && decodable) + return ovl_connect_layer(dentry); + + /* Lower file handle for indexed and non-upper dir/non-dir */ + return 1; +} + +static int ovl_dentry_to_fid(struct ovl_fs *ofs, struct dentry *dentry, + u32 *fid, int buflen) +{ + struct ovl_fh *fh = NULL; + int err, enc_lower; + int len; + + /* + * Check if we should encode a lower or upper file handle and maybe + * copy up an ancestor to make lower file handle connectable. + */ + err = enc_lower = ovl_check_encode_origin(dentry); + if (enc_lower < 0) + goto fail; + + /* Encode an upper or lower file handle */ + fh = ovl_encode_real_fh(ofs, enc_lower ? ovl_dentry_lower(dentry) : + ovl_dentry_upper(dentry), !enc_lower); + if (IS_ERR(fh)) + return PTR_ERR(fh); + + len = OVL_FH_LEN(fh); + if (len <= buflen) + memcpy(fid, fh, len); + err = len; + +out: + kfree(fh); + return err; + +fail: + pr_warn_ratelimited("failed to encode file handle (%pd2, err=%i)\n", + dentry, err); + goto out; +} + +static int ovl_encode_fh(struct inode *inode, u32 *fid, int *max_len, + struct inode *parent) +{ + struct ovl_fs *ofs = OVL_FS(inode->i_sb); + struct dentry *dentry; + int bytes, buflen = *max_len << 2; + + /* TODO: encode connectable file handles */ + if (parent) + return FILEID_INVALID; + + dentry = d_find_any_alias(inode); + if (!dentry) + return FILEID_INVALID; + + bytes = ovl_dentry_to_fid(ofs, dentry, fid, buflen); + dput(dentry); + if (bytes <= 0) + return FILEID_INVALID; + + *max_len = bytes >> 2; + if (bytes > buflen) + return FILEID_INVALID; + + return OVL_FILEID_V1; +} + +/* + * Find or instantiate an overlay dentry from real dentries and index. + */ +static struct dentry *ovl_obtain_alias(struct super_block *sb, + struct dentry *upper_alias, + struct ovl_path *lowerpath, + struct dentry *index) +{ + struct dentry *lower = lowerpath ? lowerpath->dentry : NULL; + struct dentry *upper = upper_alias ?: index; + struct dentry *dentry; + struct inode *inode = NULL; + struct ovl_entry *oe; + struct ovl_inode_params oip = { + .index = index, + }; + + /* We get overlay directory dentries with ovl_lookup_real() */ + if (d_is_dir(upper ?: lower)) + return ERR_PTR(-EIO); + + oe = ovl_alloc_entry(!!lower); + if (!oe) + return ERR_PTR(-ENOMEM); + + oip.upperdentry = dget(upper); + if (lower) { + ovl_lowerstack(oe)->dentry = dget(lower); + ovl_lowerstack(oe)->layer = lowerpath->layer; + } + oip.oe = oe; + inode = ovl_get_inode(sb, &oip); + if (IS_ERR(inode)) { + ovl_free_entry(oe); + dput(upper); + return ERR_CAST(inode); + } + + if (upper) + ovl_set_flag(OVL_UPPERDATA, inode); + + dentry = d_find_any_alias(inode); + if (dentry) + goto out_iput; + + dentry = d_alloc_anon(inode->i_sb); + if (unlikely(!dentry)) + goto nomem; + + if (upper_alias) + ovl_dentry_set_upper_alias(dentry); + + ovl_dentry_init_reval(dentry, upper, OVL_I_E(inode)); + + return d_instantiate_anon(dentry, inode); + +nomem: + dput(dentry); + dentry = ERR_PTR(-ENOMEM); +out_iput: + iput(inode); + return dentry; +} + +/* Get the upper or lower dentry in stack whose on layer @idx */ +static struct dentry *ovl_dentry_real_at(struct dentry *dentry, int idx) +{ + struct ovl_entry *oe = OVL_E(dentry); + struct ovl_path *lowerstack = ovl_lowerstack(oe); + int i; + + if (!idx) + return ovl_dentry_upper(dentry); + + for (i = 0; i < ovl_numlower(oe); i++) { + if (lowerstack[i].layer->idx == idx) + return lowerstack[i].dentry; + } + + return NULL; +} + +/* + * Lookup a child overlay dentry to get a connected overlay dentry whose real + * dentry is @real. If @real is on upper layer, we lookup a child overlay + * dentry with the same name as the real dentry. Otherwise, we need to consult + * index for lookup. + */ +static struct dentry *ovl_lookup_real_one(struct dentry *connected, + struct dentry *real, + const struct ovl_layer *layer) +{ + struct inode *dir = d_inode(connected); + struct dentry *this, *parent = NULL; + struct name_snapshot name; + int err; + + /* + * Lookup child overlay dentry by real name. The dir mutex protects us + * from racing with overlay rename. If the overlay dentry that is above + * real has already been moved to a parent that is not under the + * connected overlay dir, we return -ECHILD and restart the lookup of + * connected real path from the top. + */ + inode_lock_nested(dir, I_MUTEX_PARENT); + err = -ECHILD; + parent = dget_parent(real); + if (ovl_dentry_real_at(connected, layer->idx) != parent) + goto fail; + + /* + * We also need to take a snapshot of real dentry name to protect us + * from racing with underlying layer rename. In this case, we don't + * care about returning ESTALE, only from dereferencing a free name + * pointer because we hold no lock on the real dentry. + */ + take_dentry_name_snapshot(&name, real); + /* + * No idmap handling here: it's an internal lookup. Could skip + * permission checking altogether, but for now just use non-idmap + * transformed ids. + */ + this = lookup_one_len(name.name.name, connected, name.name.len); + release_dentry_name_snapshot(&name); + err = PTR_ERR(this); + if (IS_ERR(this)) { + goto fail; + } else if (!this || !this->d_inode) { + dput(this); + err = -ENOENT; + goto fail; + } else if (ovl_dentry_real_at(this, layer->idx) != real) { + dput(this); + err = -ESTALE; + goto fail; + } + +out: + dput(parent); + inode_unlock(dir); + return this; + +fail: + pr_warn_ratelimited("failed to lookup one by real (%pd2, layer=%d, connected=%pd2, err=%i)\n", + real, layer->idx, connected, err); + this = ERR_PTR(err); + goto out; +} + +static struct dentry *ovl_lookup_real(struct super_block *sb, + struct dentry *real, + const struct ovl_layer *layer); + +/* + * Lookup an indexed or hashed overlay dentry by real inode. + */ +static struct dentry *ovl_lookup_real_inode(struct super_block *sb, + struct dentry *real, + const struct ovl_layer *layer) +{ + struct ovl_fs *ofs = OVL_FS(sb); + struct dentry *index = NULL; + struct dentry *this = NULL; + struct inode *inode; + + /* + * Decoding upper dir from index is expensive, so first try to lookup + * overlay dentry in inode/dcache. + */ + inode = ovl_lookup_inode(sb, real, !layer->idx); + if (IS_ERR(inode)) + return ERR_CAST(inode); + if (inode) { + this = d_find_any_alias(inode); + iput(inode); + } + + /* + * For decoded lower dir file handle, lookup index by origin to check + * if lower dir was copied up and and/or removed. + */ + if (!this && layer->idx && ofs->indexdir && !WARN_ON(!d_is_dir(real))) { + index = ovl_lookup_index(ofs, NULL, real, false); + if (IS_ERR(index)) + return index; + } + + /* Get connected upper overlay dir from index */ + if (index) { + struct dentry *upper = ovl_index_upper(ofs, index, true); + + dput(index); + if (IS_ERR_OR_NULL(upper)) + return upper; + + /* + * ovl_lookup_real() in lower layer may call recursively once to + * ovl_lookup_real() in upper layer. The first level call walks + * back lower parents to the topmost indexed parent. The second + * recursive call walks back from indexed upper to the topmost + * connected/hashed upper parent (or up to root). + */ + this = ovl_lookup_real(sb, upper, &ofs->layers[0]); + dput(upper); + } + + if (IS_ERR_OR_NULL(this)) + return this; + + if (ovl_dentry_real_at(this, layer->idx) != real) { + dput(this); + this = ERR_PTR(-EIO); + } + + return this; +} + +/* + * Lookup an indexed or hashed overlay dentry, whose real dentry is an + * ancestor of @real. + */ +static struct dentry *ovl_lookup_real_ancestor(struct super_block *sb, + struct dentry *real, + const struct ovl_layer *layer) +{ + struct dentry *next, *parent = NULL; + struct dentry *ancestor = ERR_PTR(-EIO); + + if (real == layer->mnt->mnt_root) + return dget(sb->s_root); + + /* Find the topmost indexed or hashed ancestor */ + next = dget(real); + for (;;) { + parent = dget_parent(next); + + /* + * Lookup a matching overlay dentry in inode/dentry + * cache or in index by real inode. + */ + ancestor = ovl_lookup_real_inode(sb, next, layer); + if (ancestor) + break; + + if (parent == layer->mnt->mnt_root) { + ancestor = dget(sb->s_root); + break; + } + + /* + * If @real has been moved out of the layer root directory, + * we will eventully hit the real fs root. This cannot happen + * by legit overlay rename, so we return error in that case. + */ + if (parent == next) { + ancestor = ERR_PTR(-EXDEV); + break; + } + + dput(next); + next = parent; + } + + dput(parent); + dput(next); + + return ancestor; +} + +/* + * Lookup a connected overlay dentry whose real dentry is @real. + * If @real is on upper layer, we lookup a child overlay dentry with the same + * path the real dentry. Otherwise, we need to consult index for lookup. + */ +static struct dentry *ovl_lookup_real(struct super_block *sb, + struct dentry *real, + const struct ovl_layer *layer) +{ + struct dentry *connected; + int err = 0; + + connected = ovl_lookup_real_ancestor(sb, real, layer); + if (IS_ERR(connected)) + return connected; + + while (!err) { + struct dentry *next, *this; + struct dentry *parent = NULL; + struct dentry *real_connected = ovl_dentry_real_at(connected, + layer->idx); + + if (real_connected == real) + break; + + /* Find the topmost dentry not yet connected */ + next = dget(real); + for (;;) { + parent = dget_parent(next); + + if (parent == real_connected) + break; + + /* + * If real has been moved out of 'real_connected', + * we will not find 'real_connected' and hit the layer + * root. In that case, we need to restart connecting. + * This game can go on forever in the worst case. We + * may want to consider taking s_vfs_rename_mutex if + * this happens more than once. + */ + if (parent == layer->mnt->mnt_root) { + dput(connected); + connected = dget(sb->s_root); + break; + } + + /* + * If real file has been moved out of the layer root + * directory, we will eventully hit the real fs root. + * This cannot happen by legit overlay rename, so we + * return error in that case. + */ + if (parent == next) { + err = -EXDEV; + break; + } + + dput(next); + next = parent; + } + + if (!err) { + this = ovl_lookup_real_one(connected, next, layer); + if (IS_ERR(this)) + err = PTR_ERR(this); + + /* + * Lookup of child in overlay can fail when racing with + * overlay rename of child away from 'connected' parent. + * In this case, we need to restart the lookup from the + * top, because we cannot trust that 'real_connected' is + * still an ancestor of 'real'. There is a good chance + * that the renamed overlay ancestor is now in cache, so + * ovl_lookup_real_ancestor() will find it and we can + * continue to connect exactly from where lookup failed. + */ + if (err == -ECHILD) { + this = ovl_lookup_real_ancestor(sb, real, + layer); + err = PTR_ERR_OR_ZERO(this); + } + if (!err) { + dput(connected); + connected = this; + } + } + + dput(parent); + dput(next); + } + + if (err) + goto fail; + + return connected; + +fail: + pr_warn_ratelimited("failed to lookup by real (%pd2, layer=%d, connected=%pd2, err=%i)\n", + real, layer->idx, connected, err); + dput(connected); + return ERR_PTR(err); +} + +/* + * Get an overlay dentry from upper/lower real dentries and index. + */ +static struct dentry *ovl_get_dentry(struct super_block *sb, + struct dentry *upper, + struct ovl_path *lowerpath, + struct dentry *index) +{ + struct ovl_fs *ofs = OVL_FS(sb); + const struct ovl_layer *layer = upper ? &ofs->layers[0] : lowerpath->layer; + struct dentry *real = upper ?: (index ?: lowerpath->dentry); + + /* + * Obtain a disconnected overlay dentry from a non-dir real dentry + * and index. + */ + if (!d_is_dir(real)) + return ovl_obtain_alias(sb, upper, lowerpath, index); + + /* Removed empty directory? */ + if ((real->d_flags & DCACHE_DISCONNECTED) || d_unhashed(real)) + return ERR_PTR(-ENOENT); + + /* + * If real dentry is connected and hashed, get a connected overlay + * dentry whose real dentry is @real. + */ + return ovl_lookup_real(sb, real, layer); +} + +static struct dentry *ovl_upper_fh_to_d(struct super_block *sb, + struct ovl_fh *fh) +{ + struct ovl_fs *ofs = OVL_FS(sb); + struct dentry *dentry; + struct dentry *upper; + + if (!ovl_upper_mnt(ofs)) + return ERR_PTR(-EACCES); + + upper = ovl_decode_real_fh(ofs, fh, ovl_upper_mnt(ofs), true); + if (IS_ERR_OR_NULL(upper)) + return upper; + + dentry = ovl_get_dentry(sb, upper, NULL, NULL); + dput(upper); + + return dentry; +} + +static struct dentry *ovl_lower_fh_to_d(struct super_block *sb, + struct ovl_fh *fh) +{ + struct ovl_fs *ofs = OVL_FS(sb); + struct ovl_path origin = { }; + struct ovl_path *stack = &origin; + struct dentry *dentry = NULL; + struct dentry *index = NULL; + struct inode *inode; + int err; + + /* 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)) { + index = NULL; + goto out_err; + } + } + + /* Then try to get a connected upper dir by index */ + if (index && d_is_dir(index)) { + struct dentry *upper = ovl_index_upper(ofs, index, true); + + err = PTR_ERR(upper); + if (IS_ERR_OR_NULL(upper)) + goto out_err; + + dentry = ovl_get_dentry(sb, upper, NULL, NULL); + dput(upper); + goto out; + } + + /* Find origin.dentry again with ovl_acceptable() layer check */ + if (d_is_dir(origin.dentry)) { + dput(origin.dentry); + origin.dentry = NULL; + err = ovl_check_origin_fh(ofs, fh, true, NULL, &stack); + if (err) + goto out_err; + } + if (index) { + err = ovl_verify_origin(ofs, index, origin.dentry, false); + if (err) + goto out_err; + } + + /* Get a connected non-upper dir or disconnected non-dir */ + dentry = ovl_get_dentry(sb, NULL, &origin, index); + +out: + dput(origin.dentry); + dput(index); + return dentry; + +out_err: + dentry = ERR_PTR(err); + goto out; +} + +static struct ovl_fh *ovl_fid_to_fh(struct fid *fid, int buflen, int fh_type) +{ + struct ovl_fh *fh; + + /* If on-wire inner fid is aligned - nothing to do */ + if (fh_type == OVL_FILEID_V1) + return (struct ovl_fh *)fid; + + if (fh_type != OVL_FILEID_V0) + return ERR_PTR(-EINVAL); + + if (buflen <= OVL_FH_WIRE_OFFSET) + return ERR_PTR(-EINVAL); + + fh = kzalloc(buflen, GFP_KERNEL); + if (!fh) + return ERR_PTR(-ENOMEM); + + /* Copy unaligned inner fh into aligned buffer */ + memcpy(fh->buf, fid, buflen - OVL_FH_WIRE_OFFSET); + return fh; +} + +static struct dentry *ovl_fh_to_dentry(struct super_block *sb, struct fid *fid, + int fh_len, int fh_type) +{ + struct dentry *dentry = NULL; + struct ovl_fh *fh = NULL; + int len = fh_len << 2; + unsigned int flags = 0; + int err; + + fh = ovl_fid_to_fh(fid, len, fh_type); + err = PTR_ERR(fh); + if (IS_ERR(fh)) + goto out_err; + + err = ovl_check_fh_len(fh, len); + if (err) + goto out_err; + + flags = fh->fb.flags; + dentry = (flags & OVL_FH_FLAG_PATH_UPPER) ? + ovl_upper_fh_to_d(sb, fh) : + ovl_lower_fh_to_d(sb, fh); + err = PTR_ERR(dentry); + if (IS_ERR(dentry) && err != -ESTALE) + goto out_err; + +out: + /* We may have needed to re-align OVL_FILEID_V0 */ + if (!IS_ERR_OR_NULL(fh) && fh != (void *)fid) + kfree(fh); + + return dentry; + +out_err: + pr_warn_ratelimited("failed to decode file handle (len=%d, type=%d, flags=%x, err=%i)\n", + fh_len, fh_type, flags, err); + dentry = ERR_PTR(err); + goto out; +} + +static struct dentry *ovl_fh_to_parent(struct super_block *sb, struct fid *fid, + int fh_len, int fh_type) +{ + pr_warn_ratelimited("connectable file handles not supported; use 'no_subtree_check' exportfs option.\n"); + return ERR_PTR(-EACCES); +} + +static int ovl_get_name(struct dentry *parent, char *name, + struct dentry *child) +{ + /* + * ovl_fh_to_dentry() returns connected dir overlay dentries and + * ovl_fh_to_parent() is not implemented, so we should not get here. + */ + WARN_ON_ONCE(1); + return -EIO; +} + +static struct dentry *ovl_get_parent(struct dentry *dentry) +{ + /* + * ovl_fh_to_dentry() returns connected dir overlay dentries, so we + * should not get here. + */ + WARN_ON_ONCE(1); + return ERR_PTR(-EIO); +} + +const struct export_operations ovl_export_operations = { + .encode_fh = ovl_encode_fh, + .fh_to_dentry = ovl_fh_to_dentry, + .fh_to_parent = ovl_fh_to_parent, + .get_name = ovl_get_name, + .get_parent = ovl_get_parent, +}; + +/* encode_fh() encodes non-decodable file handles with nfs_export=off */ +const struct export_operations ovl_export_fid_operations = { + .encode_fh = ovl_encode_fh, +}; |