From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- fs/9p/fid.c | 327 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 327 insertions(+) create mode 100644 fs/9p/fid.c (limited to 'fs/9p/fid.c') diff --git a/fs/9p/fid.c b/fs/9p/fid.c new file mode 100644 index 000000000..23cf9b2fb --- /dev/null +++ b/fs/9p/fid.c @@ -0,0 +1,327 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * V9FS FID Management + * + * Copyright (C) 2007 by Latchesar Ionkov + * Copyright (C) 2005, 2006 by Eric Van Hensbergen + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +#include "v9fs.h" +#include "v9fs_vfs.h" +#include "fid.h" + +static inline void __add_fid(struct dentry *dentry, struct p9_fid *fid) +{ + hlist_add_head(&fid->dlist, (struct hlist_head *)&dentry->d_fsdata); +} + + +/** + * v9fs_fid_add - add a fid to a dentry + * @dentry: dentry that the fid is being added to + * @pfid: fid to add, NULLed out + * + */ +void v9fs_fid_add(struct dentry *dentry, struct p9_fid **pfid) +{ + struct p9_fid *fid = *pfid; + + spin_lock(&dentry->d_lock); + __add_fid(dentry, fid); + spin_unlock(&dentry->d_lock); + + *pfid = NULL; +} + +/** + * v9fs_fid_find_inode - search for an open fid off of the inode list + * @inode: return a fid pointing to a specific inode + * @uid: return a fid belonging to the specified user + * + */ + +static struct p9_fid *v9fs_fid_find_inode(struct inode *inode, kuid_t uid) +{ + struct hlist_head *h; + struct p9_fid *fid, *ret = NULL; + + p9_debug(P9_DEBUG_VFS, " inode: %p\n", inode); + + spin_lock(&inode->i_lock); + h = (struct hlist_head *)&inode->i_private; + hlist_for_each_entry(fid, h, ilist) { + if (uid_eq(fid->uid, uid)) { + p9_fid_get(fid); + ret = fid; + break; + } + } + spin_unlock(&inode->i_lock); + return ret; +} + +/** + * v9fs_open_fid_add - add an open fid to an inode + * @inode: inode that the fid is being added to + * @pfid: fid to add, NULLed out + * + */ + +void v9fs_open_fid_add(struct inode *inode, struct p9_fid **pfid) +{ + struct p9_fid *fid = *pfid; + + spin_lock(&inode->i_lock); + hlist_add_head(&fid->ilist, (struct hlist_head *)&inode->i_private); + spin_unlock(&inode->i_lock); + + *pfid = NULL; +} + + +/** + * v9fs_fid_find - retrieve a fid that belongs to the specified uid + * @dentry: dentry to look for fid in + * @uid: return fid that belongs to the specified user + * @any: if non-zero, return any fid associated with the dentry + * + */ + +static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any) +{ + struct p9_fid *fid, *ret; + + p9_debug(P9_DEBUG_VFS, " dentry: %pd (%p) uid %d any %d\n", + dentry, dentry, from_kuid(&init_user_ns, uid), + any); + ret = NULL; + /* we'll recheck under lock if there's anything to look in */ + if (dentry->d_fsdata) { + struct hlist_head *h = (struct hlist_head *)&dentry->d_fsdata; + + spin_lock(&dentry->d_lock); + hlist_for_each_entry(fid, h, dlist) { + if (any || uid_eq(fid->uid, uid)) { + ret = fid; + p9_fid_get(ret); + break; + } + } + spin_unlock(&dentry->d_lock); + } else { + if (dentry->d_inode) + ret = v9fs_fid_find_inode(dentry->d_inode, uid); + } + + return ret; +} + +/* + * We need to hold v9ses->rename_sem as long as we hold references + * to returned path array. Array element contain pointers to + * dentry names. + */ +static int build_path_from_dentry(struct v9fs_session_info *v9ses, + struct dentry *dentry, const unsigned char ***names) +{ + int n = 0, i; + const unsigned char **wnames; + struct dentry *ds; + + for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent) + n++; + + wnames = kmalloc_array(n, sizeof(char *), GFP_KERNEL); + if (!wnames) + goto err_out; + + for (ds = dentry, i = (n-1); i >= 0; i--, ds = ds->d_parent) + wnames[i] = ds->d_name.name; + + *names = wnames; + return n; +err_out: + return -ENOMEM; +} + +static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry, + kuid_t uid, int any) +{ + struct dentry *ds; + const unsigned char **wnames, *uname; + int i, n, l, access; + struct v9fs_session_info *v9ses; + struct p9_fid *fid, *root_fid, *old_fid; + + v9ses = v9fs_dentry2v9ses(dentry); + access = v9ses->flags & V9FS_ACCESS_MASK; + fid = v9fs_fid_find(dentry, uid, any); + if (fid) + return fid; + /* + * we don't have a matching fid. To do a TWALK we need + * parent fid. We need to prevent rename when we want to + * look at the parent. + */ + down_read(&v9ses->rename_sem); + ds = dentry->d_parent; + fid = v9fs_fid_find(ds, uid, any); + if (fid) { + /* Found the parent fid do a lookup with that */ + old_fid = fid; + + fid = p9_client_walk(old_fid, 1, &dentry->d_name.name, 1); + p9_fid_put(old_fid); + goto fid_out; + } + up_read(&v9ses->rename_sem); + + /* start from the root and try to do a lookup */ + root_fid = v9fs_fid_find(dentry->d_sb->s_root, uid, any); + if (!root_fid) { + /* the user is not attached to the fs yet */ + if (access == V9FS_ACCESS_SINGLE) + return ERR_PTR(-EPERM); + + if (v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses)) + uname = NULL; + else + uname = v9ses->uname; + + fid = p9_client_attach(v9ses->clnt, NULL, uname, uid, + v9ses->aname); + if (IS_ERR(fid)) + return fid; + + root_fid = p9_fid_get(fid); + v9fs_fid_add(dentry->d_sb->s_root, &fid); + } + /* If we are root ourself just return that */ + if (dentry->d_sb->s_root == dentry) + return root_fid; + + /* + * Do a multipath walk with attached root. + * When walking parent we need to make sure we + * don't have a parallel rename happening + */ + down_read(&v9ses->rename_sem); + n = build_path_from_dentry(v9ses, dentry, &wnames); + if (n < 0) { + fid = ERR_PTR(n); + goto err_out; + } + fid = root_fid; + old_fid = root_fid; + i = 0; + while (i < n) { + l = min(n - i, P9_MAXWELEM); + /* + * We need to hold rename lock when doing a multipath + * walk to ensure none of the path components change + */ + fid = p9_client_walk(old_fid, l, &wnames[i], + old_fid == root_fid /* clone */); + /* non-cloning walk will return the same fid */ + if (fid != old_fid) { + p9_fid_put(old_fid); + old_fid = fid; + } + if (IS_ERR(fid)) { + kfree(wnames); + goto err_out; + } + i += l; + } + kfree(wnames); +fid_out: + if (!IS_ERR(fid)) { + spin_lock(&dentry->d_lock); + if (d_unhashed(dentry)) { + spin_unlock(&dentry->d_lock); + p9_fid_put(fid); + fid = ERR_PTR(-ENOENT); + } else { + __add_fid(dentry, fid); + p9_fid_get(fid); + spin_unlock(&dentry->d_lock); + } + } +err_out: + up_read(&v9ses->rename_sem); + return fid; +} + +/** + * v9fs_fid_lookup - lookup for a fid, try to walk if not found + * @dentry: dentry to look for fid in + * + * Look for a fid in the specified dentry for the current user. + * If no fid is found, try to create one walking from a fid from the parent + * dentry (if it has one), or the root dentry. If the user haven't accessed + * the fs yet, attach now and walk from the root. + */ + +struct p9_fid *v9fs_fid_lookup(struct dentry *dentry) +{ + kuid_t uid; + int any, access; + struct v9fs_session_info *v9ses; + + v9ses = v9fs_dentry2v9ses(dentry); + access = v9ses->flags & V9FS_ACCESS_MASK; + switch (access) { + case V9FS_ACCESS_SINGLE: + case V9FS_ACCESS_USER: + case V9FS_ACCESS_CLIENT: + uid = current_fsuid(); + any = 0; + break; + + case V9FS_ACCESS_ANY: + uid = v9ses->uid; + any = 1; + break; + + default: + uid = INVALID_UID; + any = 0; + break; + } + return v9fs_fid_lookup_with_uid(dentry, uid, any); +} + +struct p9_fid *v9fs_writeback_fid(struct dentry *dentry) +{ + int err; + struct p9_fid *fid, *ofid; + + ofid = v9fs_fid_lookup_with_uid(dentry, GLOBAL_ROOT_UID, 0); + fid = clone_fid(ofid); + if (IS_ERR(fid)) + goto error_out; + p9_fid_put(ofid); + /* + * writeback fid will only be used to write back the + * dirty pages. We always request for the open fid in read-write + * mode so that a partial page write which result in page + * read can work. + */ + err = p9_client_open(fid, O_RDWR); + if (err < 0) { + p9_fid_put(fid); + fid = ERR_PTR(err); + goto error_out; + } +error_out: + return fid; +} -- cgit v1.2.3