From: Ram Pai Date: Thu, 27 Mar 2008 12:06:20 +0000 (+0100) Subject: [patch 1/7] vfs: mountinfo: add dentry_path() X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=6092d048183b76bfa3f84b32f8158dd8d10bd811;p=GitHub%2FLineageOS%2Fandroid_kernel_samsung_universal7580.git [patch 1/7] vfs: mountinfo: add dentry_path() [mszeredi@suse.cz] split big patch into managable chunks Add the following functions: dentry_path() seq_dentry() These are similar to d_path() and seq_path(). But instead of calculating the path within a mount namespace, they calculate the path from the root of the filesystem to a given dentry, ignoring mounts completely. Signed-off-by: Ram Pai Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- diff --git a/fs/dcache.c b/fs/dcache.c index 43455776711..635c2aa427e 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1746,6 +1746,17 @@ shouldnt_be_hashed: goto shouldnt_be_hashed; } +static int prepend(char **buffer, int *buflen, const char *str, + int namelen) +{ + *buflen -= namelen; + if (*buflen < 0) + return -ENAMETOOLONG; + *buffer -= namelen; + memcpy(*buffer, str, namelen); + return 0; +} + /** * d_path - return the path of a dentry * @dentry: dentry to report @@ -1767,17 +1778,11 @@ static char *__d_path(struct dentry *dentry, struct vfsmount *vfsmnt, { char * end = buffer+buflen; char * retval; - int namelen; - - *--end = '\0'; - buflen--; - if (!IS_ROOT(dentry) && d_unhashed(dentry)) { - buflen -= 10; - end -= 10; - if (buflen < 0) + + prepend(&end, &buflen, "\0", 1); + if (!IS_ROOT(dentry) && d_unhashed(dentry) && + (prepend(&end, &buflen, " (deleted)", 10) != 0)) goto Elong; - memcpy(end, " (deleted)", 10); - } if (buflen < 1) goto Elong; @@ -1804,13 +1809,10 @@ static char *__d_path(struct dentry *dentry, struct vfsmount *vfsmnt, } parent = dentry->d_parent; prefetch(parent); - namelen = dentry->d_name.len; - buflen -= namelen + 1; - if (buflen < 0) + if ((prepend(&end, &buflen, dentry->d_name.name, + dentry->d_name.len) != 0) || + (prepend(&end, &buflen, "/", 1) != 0)) goto Elong; - end -= namelen; - memcpy(end, dentry->d_name.name, namelen); - *--end = '/'; retval = end; dentry = parent; } @@ -1818,12 +1820,10 @@ static char *__d_path(struct dentry *dentry, struct vfsmount *vfsmnt, return retval; global_root: - namelen = dentry->d_name.len; - buflen -= namelen; - if (buflen < 0) + retval += 1; /* hit the slash */ + if (prepend(&retval, &buflen, dentry->d_name.name, + dentry->d_name.len) != 0) goto Elong; - retval -= namelen-1; /* hit the slash */ - memcpy(retval, dentry->d_name.name, namelen); return retval; Elong: return ERR_PTR(-ENAMETOOLONG); @@ -1859,7 +1859,7 @@ char *d_path(struct path *path, char *buf, int buflen) read_lock(¤t->fs->lock); root = current->fs->root; - path_get(¤t->fs->root); + path_get(&root); read_unlock(¤t->fs->lock); spin_lock(&dcache_lock); res = __d_path(path->dentry, path->mnt, &root, buf, buflen); @@ -1889,6 +1889,48 @@ char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen, return memcpy(buffer, temp, sz); } +/* + * Write full pathname from the root of the filesystem into the buffer. + */ +char *dentry_path(struct dentry *dentry, char *buf, int buflen) +{ + char *end = buf + buflen; + char *retval; + + spin_lock(&dcache_lock); + prepend(&end, &buflen, "\0", 1); + if (!IS_ROOT(dentry) && d_unhashed(dentry) && + (prepend(&end, &buflen, "//deleted", 9) != 0)) + goto Elong; + if (buflen < 1) + goto Elong; + /* Get '/' right */ + retval = end-1; + *retval = '/'; + + for (;;) { + struct dentry *parent; + if (IS_ROOT(dentry)) + break; + + parent = dentry->d_parent; + prefetch(parent); + + if ((prepend(&end, &buflen, dentry->d_name.name, + dentry->d_name.len) != 0) || + (prepend(&end, &buflen, "/", 1) != 0)) + goto Elong; + + retval = end; + dentry = parent; + } + spin_unlock(&dcache_lock); + return retval; +Elong: + spin_unlock(&dcache_lock); + return ERR_PTR(-ENAMETOOLONG); +} + /* * NOTE! The user-level library version returns a * character pointer. The kernel system call just @@ -1918,9 +1960,9 @@ asmlinkage long sys_getcwd(char __user *buf, unsigned long size) read_lock(¤t->fs->lock); pwd = current->fs->pwd; - path_get(¤t->fs->pwd); + path_get(&pwd); root = current->fs->root; - path_get(¤t->fs->root); + path_get(&root); read_unlock(¤t->fs->lock); error = -ENOENT; diff --git a/fs/seq_file.c b/fs/seq_file.c index cdfd996ca6e..ae59f5a6c5c 100644 --- a/fs/seq_file.c +++ b/fs/seq_file.c @@ -350,28 +350,40 @@ int seq_printf(struct seq_file *m, const char *f, ...) } EXPORT_SYMBOL(seq_printf); +static char *mangle_path(char *s, char *p, char *esc) +{ + while (s <= p) { + char c = *p++; + if (!c) { + return s; + } else if (!strchr(esc, c)) { + *s++ = c; + } else if (s + 4 > p) { + break; + } else { + *s++ = '\\'; + *s++ = '0' + ((c & 0300) >> 6); + *s++ = '0' + ((c & 070) >> 3); + *s++ = '0' + (c & 07); + } + } + return NULL; +} + +/* + * return the absolute path of 'dentry' residing in mount 'mnt'. + */ int seq_path(struct seq_file *m, struct path *path, char *esc) { if (m->count < m->size) { char *s = m->buf + m->count; char *p = d_path(path, s, m->size - m->count); if (!IS_ERR(p)) { - while (s <= p) { - char c = *p++; - if (!c) { - p = m->buf + m->count; - m->count = s - m->buf; - return s - p; - } else if (!strchr(esc, c)) { - *s++ = c; - } else if (s + 4 > p) { - break; - } else { - *s++ = '\\'; - *s++ = '0' + ((c & 0300) >> 6); - *s++ = '0' + ((c & 070) >> 3); - *s++ = '0' + (c & 07); - } + s = mangle_path(s, p, esc); + if (s) { + p = m->buf + m->count; + m->count = s - m->buf; + return s - p; } } } @@ -380,6 +392,27 @@ int seq_path(struct seq_file *m, struct path *path, char *esc) } EXPORT_SYMBOL(seq_path); +/* + * returns the path of the 'dentry' from the root of its filesystem. + */ +int seq_dentry(struct seq_file *m, struct dentry *dentry, char *esc) +{ + if (m->count < m->size) { + char *s = m->buf + m->count; + char *p = dentry_path(dentry, s, m->size - m->count); + if (!IS_ERR(p)) { + s = mangle_path(s, p, esc); + if (s) { + p = m->buf + m->count; + m->count = s - m->buf; + return s - p; + } + } + } + m->count = m->size; + return -1; +} + static void *single_start(struct seq_file *p, loff_t *pos) { return NULL + (*pos == 0); diff --git a/include/linux/dcache.h b/include/linux/dcache.h index fabd16d03a2..63960033b6f 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -302,6 +302,7 @@ extern int d_validate(struct dentry *, struct dentry *); extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...); extern char *d_path(struct path *, char *, int); +extern char *dentry_path(struct dentry *, char *, int); /* Allocation counts.. */ diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h index d65796dc26d..11676ccef7b 100644 --- a/include/linux/seq_file.h +++ b/include/linux/seq_file.h @@ -10,6 +10,7 @@ struct seq_operations; struct file; struct path; struct inode; +struct dentry; struct seq_file { char *buf; @@ -44,6 +45,7 @@ int seq_printf(struct seq_file *, const char *, ...) __attribute__ ((format (printf,2,3))); int seq_path(struct seq_file *, struct path *, char *); +int seq_dentry(struct seq_file *, struct dentry *, char *); int single_open(struct file *, int (*)(struct seq_file *, void *), void *); int single_release(struct inode *, struct file *);