From f77f21bb28367d0ac4861a24da1db118bba850e6 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Mon, 29 Apr 2019 12:13:14 -0400 Subject: [PATCH] ceph: use __getname/__putname in ceph_mdsc_build_path Al suggested we get rid of the kmalloc here and just use __getname and __putname to get a full PATH_MAX pathname buffer. Since we build the path in reverse, we continue to return a pointer to the beginning of the string and the length, and add a new helper to free the thing at the end. Suggested-by: Al Viro Signed-off-by: Jeff Layton Reviewed-by: "Yan, Zheng" Signed-off-by: Ilya Dryomov --- fs/ceph/debugfs.c | 4 +-- fs/ceph/mds_client.c | 65 +++++++++++++++++++------------------------- fs/ceph/mds_client.h | 6 ++++ 3 files changed, 36 insertions(+), 39 deletions(-) diff --git a/fs/ceph/debugfs.c b/fs/ceph/debugfs.c index 777f6ceb5259..b014fc7d4e3c 100644 --- a/fs/ceph/debugfs.c +++ b/fs/ceph/debugfs.c @@ -88,7 +88,7 @@ static int mdsc_show(struct seq_file *s, void *p) req->r_dentry, path ? path : ""); spin_unlock(&req->r_dentry->d_lock); - kfree(path); + ceph_mdsc_free_path(path, pathlen); } else if (req->r_path1) { seq_printf(s, " #%llx/%s", req->r_ino1.ino, req->r_path1); @@ -108,7 +108,7 @@ static int mdsc_show(struct seq_file *s, void *p) req->r_old_dentry, path ? path : ""); spin_unlock(&req->r_old_dentry->d_lock); - kfree(path); + ceph_mdsc_free_path(path, pathlen); } else if (req->r_path2 && req->r_op != CEPH_MDS_OP_SYMLINK) { if (req->r_ino2.ino) seq_printf(s, " #%llx/%s", req->r_ino2.ino, diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index 7af722834348..d29f6c094f7c 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -2094,39 +2094,24 @@ char *ceph_mdsc_build_path(struct dentry *dentry, int *plen, u64 *pbase, { struct dentry *temp; char *path; - int len, pos; + int pos; unsigned seq; u64 base; if (!dentry) return ERR_PTR(-EINVAL); -retry: - len = 0; - seq = read_seqbegin(&rename_lock); - rcu_read_lock(); - for (temp = dentry; !IS_ROOT(temp);) { - struct inode *inode = d_inode(temp); - if (inode && ceph_snap(inode) == CEPH_SNAPDIR) - len++; /* slash only */ - else if (stop_on_nosnap && inode && - ceph_snap(inode) == CEPH_NOSNAP) - break; - else - len += 1 + temp->d_name.len; - temp = temp->d_parent; - } - rcu_read_unlock(); - if (len) - len--; /* no leading '/' */ - - path = kmalloc(len+1, GFP_NOFS); + path = __getname(); if (!path) return ERR_PTR(-ENOMEM); - pos = len; - path[pos] = 0; /* trailing null */ +retry: + pos = PATH_MAX - 1; + path[pos] = '\0'; + + seq = read_seqbegin(&rename_lock); rcu_read_lock(); - for (temp = dentry; !IS_ROOT(temp) && pos != 0; ) { + temp = dentry; + for (;;) { struct inode *inode; spin_lock(&temp->d_lock); @@ -2144,32 +2129,38 @@ retry: spin_unlock(&temp->d_lock); break; } - strncpy(path + pos, temp->d_name.name, - temp->d_name.len); + memcpy(path + pos, temp->d_name.name, temp->d_name.len); } spin_unlock(&temp->d_lock); - if (pos) - path[--pos] = '/'; temp = temp->d_parent; + + /* Are we at the root? */ + if (IS_ROOT(temp)) + break; + + /* Are we out of buffer? */ + if (--pos < 0) + break; + + path[pos] = '/'; } base = ceph_ino(d_inode(temp)); rcu_read_unlock(); - if (pos != 0 || read_seqretry(&rename_lock, seq)) { + if (pos < 0 || read_seqretry(&rename_lock, seq)) { pr_err("build_path did not end path lookup where " - "expected, namelen is %d, pos is %d\n", len, pos); + "expected, pos is %d\n", pos); /* presumably this is only possible if racing with a rename of one of the parent directories (we can not lock the dentries above us to prevent this, but retrying should be harmless) */ - kfree(path); goto retry; } *pbase = base; - *plen = len; + *plen = PATH_MAX - 1 - pos; dout("build_path on %p %d built %llx '%.*s'\n", - dentry, d_count(dentry), base, len, path); - return path; + dentry, d_count(dentry), base, *plen, path + pos); + return path + pos; } static int build_dentry_path(struct dentry *dentry, struct inode *dir, @@ -2376,10 +2367,10 @@ static struct ceph_msg *create_request_message(struct ceph_mds_client *mdsc, out_free2: if (freepath2) - kfree((char *)path2); + ceph_mdsc_free_path((char *)path2, pathlen2); out_free1: if (freepath1) - kfree((char *)path1); + ceph_mdsc_free_path((char *)path1, pathlen1); out: return msg; } @@ -3451,7 +3442,7 @@ out_freeflocks: ceph_pagelist_encode_string(pagelist, path, pathlen); ceph_pagelist_append(pagelist, &rec, sizeof(rec.v1)); out_freepath: - kfree(path); + ceph_mdsc_free_path(path, pathlen); } out_err: diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h index 0d1f673a5689..ebcad5afc87b 100644 --- a/fs/ceph/mds_client.h +++ b/fs/ceph/mds_client.h @@ -492,6 +492,12 @@ extern int ceph_iterate_session_caps(struct ceph_mds_session *session, void *arg); extern void ceph_mdsc_pre_umount(struct ceph_mds_client *mdsc); +static inline void ceph_mdsc_free_path(char *path, int len) +{ + if (path) + __putname(path - (PATH_MAX - 1 - len)); +} + extern char *ceph_mdsc_build_path(struct dentry *dentry, int *plen, u64 *base, int stop_on_nosnap);