From c103135c14e03fc9a9e5f0adc01df9ad272cf2a1 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sun, 6 Jun 2010 22:31:14 -0400 Subject: new helper: __dentry_path() builds path relative to fs root, called under dcache_lock, doesn't append any nonsense to unlinked ones. Signed-off-by: Al Viro --- fs/dcache.c | 27 ++++++++++++++++++++++----- 1 file changed, 22 insertions(+), 5 deletions(-) (limited to 'fs/dcache.c') diff --git a/fs/dcache.c b/fs/dcache.c index 86d4db15473e..caf08574982f 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2049,16 +2049,12 @@ char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen, /* * Write full pathname from the root of the filesystem into the buffer. */ -char *dentry_path(struct dentry *dentry, char *buf, int buflen) +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 (d_unlinked(dentry) && - (prepend(&end, &buflen, "//deleted", 9) != 0)) - goto Elong; if (buflen < 1) goto Elong; /* Get '/' right */ @@ -2076,7 +2072,28 @@ char *dentry_path(struct dentry *dentry, char *buf, int buflen) retval = end; dentry = parent; } + return retval; +Elong: + return ERR_PTR(-ENAMETOOLONG); +} +EXPORT_SYMBOL(__dentry_path); + +char *dentry_path(struct dentry *dentry, char *buf, int buflen) +{ + char *p = NULL; + char *retval; + + spin_lock(&dcache_lock); + if (d_unlinked(dentry)) { + p = buf + buflen; + if (prepend(&p, &buflen, "//deleted", 10) != 0) + goto Elong; + buflen++; + } + retval = __dentry_path(dentry, buf, buflen); spin_unlock(&dcache_lock); + if (!IS_ERR(retval) && p) + *p = '/'; /* restore '/' overriden with '\0' */ return retval; Elong: spin_unlock(&dcache_lock); -- cgit v1.2.2 From dca332528bc69e05f67161e1ed59929633d5e63d Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sun, 25 Jul 2010 02:31:46 +0400 Subject: no need for list_for_each_entry_safe()/resetting with superblock list just delay __put_super() a bit Signed-off-by: Al Viro --- fs/dcache.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) (limited to 'fs/dcache.c') diff --git a/fs/dcache.c b/fs/dcache.c index caf08574982f..9f2c13417969 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -536,7 +536,7 @@ restart: */ static void prune_dcache(int count) { - struct super_block *sb, *n; + struct super_block *sb, *p = NULL; int w_count; int unused = dentry_stat.nr_unused; int prune_ratio; @@ -550,7 +550,7 @@ static void prune_dcache(int count) else prune_ratio = unused / count; spin_lock(&sb_lock); - list_for_each_entry_safe(sb, n, &super_blocks, s_list) { + list_for_each_entry(sb, &super_blocks, s_list) { if (list_empty(&sb->s_instances)) continue; if (sb->s_nr_dentry_unused == 0) @@ -590,14 +590,16 @@ static void prune_dcache(int count) up_read(&sb->s_umount); } spin_lock(&sb_lock); - /* lock was dropped, must reset next */ - list_safe_reset_next(sb, n, s_list); + if (p) + __put_super(p); count -= pruned; - __put_super(sb); + p = sb; /* more work left to do? */ if (count <= 0) break; } + if (p) + __put_super(p); spin_unlock(&sb_lock); spin_unlock(&dcache_lock); } -- cgit v1.2.2 From f7ad3c6be90809b53b7f0ae9d4eaa45ce2564a79 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 10 Aug 2010 11:41:36 +0200 Subject: vfs: add helpers to get root and pwd Add three helpers that retrieve a refcounted copy of the root and cwd from the supplied fs_struct. get_fs_root() get_fs_pwd() get_fs_root_and_pwd() Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/dcache.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) (limited to 'fs/dcache.c') diff --git a/fs/dcache.c b/fs/dcache.c index 9f2c13417969..995d08069d26 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2014,10 +2014,7 @@ char *d_path(const struct path *path, char *buf, int buflen) if (path->dentry->d_op && path->dentry->d_op->d_dname) return path->dentry->d_op->d_dname(path->dentry, buf, buflen); - read_lock(¤t->fs->lock); - root = current->fs->root; - path_get(&root); - read_unlock(¤t->fs->lock); + get_fs_root(current->fs, &root); spin_lock(&dcache_lock); tmp = root; res = __d_path(path, &tmp, buf, buflen); @@ -2129,12 +2126,7 @@ SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) if (!page) return -ENOMEM; - read_lock(¤t->fs->lock); - pwd = current->fs->pwd; - path_get(&pwd); - root = current->fs->root; - path_get(&root); - read_unlock(¤t->fs->lock); + get_fs_root_and_pwd(current->fs, &root, &pwd); error = -ENOENT; spin_lock(&dcache_lock); -- cgit v1.2.2 From 98dc568bc2ebefe4c0cb315a7fb7eff8bbb43176 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 10 Aug 2010 11:41:38 +0200 Subject: vfs: __d_path: dont prepend the name of the root dentry In the old times pseudo-filesystems set the name of theroot dentry to some prefix like "pipe:" and the name of the child dentry to "[123]" and relied on a hack in __d_path() to replace the preceding slash with the root's name to get "pipe:[123]". Then the d_dname() dentry operation was introduced which solved the same problem without having to pre-fill the name in each dentry. Currently the following pseudo filesystems exist in the kernel: perfmon mtd anon_inode bdev pipe socket Of these only perfmon, anon_inode, pipe and socket create sub-dentries, all of which have now been switched to using d_dname(). bdev and mtd only create inodes. This means that now the hack to overwrite the slash can be removed, so for unreachable paths (e.g. within a detached mount) the path string won't be polluted with garbage. For these cases a subsequent patch will add a prefix, indicating that the path is unreachable. Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/dcache.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) (limited to 'fs/dcache.c') diff --git a/fs/dcache.c b/fs/dcache.c index 995d08069d26..f1809e6b9fda 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1970,9 +1970,15 @@ out: return retval; global_root: - retval += 1; /* hit the slash */ - if (prepend_name(&retval, &buflen, &dentry->d_name) != 0) - goto Elong; + /* + * Filesystems needing to implement special "root names" + * should do so with ->d_dname() + */ + if (IS_ROOT(dentry) && + (dentry->d_name.len != 1 || dentry->d_name.name[0] != '/')) { + WARN(1, "Root dentry has weird name <%.*s>\n", + (int) dentry->d_name.len, dentry->d_name.name); + } root->mnt = vfsmnt; root->dentry = dentry; goto out; -- cgit v1.2.2 From f2eb6575d5beba1e98d400463007d77555d1fc35 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 10 Aug 2010 11:41:39 +0200 Subject: vfs: add prepend_path() helper Split off prepend_path() from __d_path(). This new helper takes an end-of-buffer pointer and buffer-length pointer just like the other prepend_* functions. Move the " (deleted)" postfix out to __d_path(). This patch doesn't change any functionality but paves the way for the following patches. Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/dcache.c | 94 ++++++++++++++++++++++++++++++++++++++----------------------- 1 file changed, 58 insertions(+), 36 deletions(-) (limited to 'fs/dcache.c') diff --git a/fs/dcache.c b/fs/dcache.c index f1809e6b9fda..d09d93819b4d 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1905,48 +1905,30 @@ static int prepend_name(char **buffer, int *buflen, struct qstr *name) } /** - * __d_path - return the path of a dentry + * Prepend path string to a buffer + * * @path: the dentry/vfsmount to report * @root: root vfsmnt/dentry (may be modified by this function) - * @buffer: buffer to return value in - * @buflen: buffer length - * - * Convert a dentry into an ASCII path name. If the entry has been deleted - * the string " (deleted)" is appended. Note that this is ambiguous. - * - * Returns a pointer into the buffer or an error code if the - * path was too long. + * @buffer: pointer to the end of the buffer + * @buflen: pointer to buffer length * - * "buflen" should be positive. Caller holds the dcache_lock. + * Caller holds the dcache_lock. * * If path is not reachable from the supplied root, then the value of * root is changed (without modifying refcounts). */ -char *__d_path(const struct path *path, struct path *root, - char *buffer, int buflen) +static int prepend_path(const struct path *path, struct path *root, + char **buffer, int *buflen) { struct dentry *dentry = path->dentry; struct vfsmount *vfsmnt = path->mnt; - char *end = buffer + buflen; - char *retval; + bool slash = false; + int error = 0; spin_lock(&vfsmount_lock); - prepend(&end, &buflen, "\0", 1); - if (d_unlinked(dentry) && - (prepend(&end, &buflen, " (deleted)", 10) != 0)) - goto Elong; - - if (buflen < 1) - goto Elong; - /* Get '/' right */ - retval = end-1; - *retval = '/'; - - for (;;) { + while (dentry != root->dentry || vfsmnt != root->mnt) { struct dentry * parent; - if (dentry == root->dentry && vfsmnt == root->mnt) - break; if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { /* Global root? */ if (vfsmnt->mnt_parent == vfsmnt) { @@ -1958,16 +1940,22 @@ char *__d_path(const struct path *path, struct path *root, } parent = dentry->d_parent; prefetch(parent); - if ((prepend_name(&end, &buflen, &dentry->d_name) != 0) || - (prepend(&end, &buflen, "/", 1) != 0)) - goto Elong; - retval = end; + error = prepend_name(buffer, buflen, &dentry->d_name); + if (!error) + error = prepend(buffer, buflen, "/", 1); + if (error) + break; + + slash = true; dentry = parent; } out: + if (!error && !slash) + error = prepend(buffer, buflen, "/", 1); + spin_unlock(&vfsmount_lock); - return retval; + return error; global_root: /* @@ -1982,10 +1970,44 @@ global_root: root->mnt = vfsmnt; root->dentry = dentry; goto out; +} -Elong: - retval = ERR_PTR(-ENAMETOOLONG); - goto out; +/** + * __d_path - return the path of a dentry + * @path: the dentry/vfsmount to report + * @root: root vfsmnt/dentry (may be modified by this function) + * @buffer: buffer to return value in + * @buflen: buffer length + * + * Convert a dentry into an ASCII path name. If the entry has been deleted + * the string " (deleted)" is appended. Note that this is ambiguous. + * + * Returns a pointer into the buffer or an error code if the + * path was too long. + * + * "buflen" should be positive. Caller holds the dcache_lock. + * + * If path is not reachable from the supplied root, then the value of + * root is changed (without modifying refcounts). + */ +char *__d_path(const struct path *path, struct path *root, + char *buf, int buflen) +{ + char *res = buf + buflen; + int error; + + prepend(&res, &buflen, "\0", 1); + if (d_unlinked(path->dentry)) { + error = prepend(&res, &buflen, " (deleted)", 10); + if (error) + return ERR_PTR(error); + } + + error = prepend_path(path, root, &res, &buflen); + if (error) + return ERR_PTR(error); + + return res; } /** -- cgit v1.2.2 From ffd1f4ed5bddccf2277e3d8525bcedf1983319f8 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 10 Aug 2010 11:41:40 +0200 Subject: vfs: only add " (deleted)" where necessary __d_path() has 4 callers: d_path() sys_getcwd() seq_path_root() tomoyo_realpath_from_path2() Of these the only one which needs the " (deleted)" ending is d_path(). sys_getcwd() checks for existence before calling __d_path(). seq_path_root() is used to show the mountpoint path in /proc/PID/mountinfo, which is always a positive. And tomoyo doesn't want the deleted ending. Create a helper "path_with_deleted()" as subsequent patches will need this in multiple places. Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/dcache.c | 32 ++++++++++++++++++++++---------- 1 file changed, 22 insertions(+), 10 deletions(-) (limited to 'fs/dcache.c') diff --git a/fs/dcache.c b/fs/dcache.c index d09d93819b4d..7fccb00f498d 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1979,8 +1979,7 @@ global_root: * @buffer: buffer to return value in * @buflen: buffer length * - * Convert a dentry into an ASCII path name. If the entry has been deleted - * the string " (deleted)" is appended. Note that this is ambiguous. + * Convert a dentry into an ASCII path name. * * Returns a pointer into the buffer or an error code if the * path was too long. @@ -1997,12 +1996,6 @@ char *__d_path(const struct path *path, struct path *root, int error; prepend(&res, &buflen, "\0", 1); - if (d_unlinked(path->dentry)) { - error = prepend(&res, &buflen, " (deleted)", 10); - if (error) - return ERR_PTR(error); - } - error = prepend_path(path, root, &res, &buflen); if (error) return ERR_PTR(error); @@ -2010,6 +2003,22 @@ char *__d_path(const struct path *path, struct path *root, return res; } +/* + * same as __d_path but appends "(deleted)" for unlinked files. + */ +static int path_with_deleted(const struct path *path, struct path *root, + char **buf, int *buflen) +{ + prepend(buf, buflen, "\0", 1); + if (d_unlinked(path->dentry)) { + int error = prepend(buf, buflen, " (deleted)", 10); + if (error) + return error; + } + + return prepend_path(path, root, buf, buflen); +} + /** * d_path - return the path of a dentry * @path: path to report @@ -2028,9 +2037,10 @@ char *__d_path(const struct path *path, struct path *root, */ char *d_path(const struct path *path, char *buf, int buflen) { - char *res; + char *res = buf + buflen; struct path root; struct path tmp; + int error; /* * We have various synthetic filesystems that never get mounted. On @@ -2045,7 +2055,9 @@ char *d_path(const struct path *path, char *buf, int buflen) get_fs_root(current->fs, &root); spin_lock(&dcache_lock); tmp = root; - res = __d_path(path, &tmp, buf, buflen); + error = path_with_deleted(path, &tmp, &res, &buflen); + if (error) + res = ERR_PTR(error); spin_unlock(&dcache_lock); path_put(&root); return res; -- cgit v1.2.2 From 8df9d1a4142311c084ffeeacb67cd34d190eff74 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 10 Aug 2010 11:41:41 +0200 Subject: vfs: show unreachable paths in getcwd and proc Prepend "(unreachable)" to path strings if the path is not reachable from the current root. Two places updated are - the return string from getcwd() - and symlinks under /proc/$PID. Other uses of d_path() are left unchanged (we know that some old software crashes if /proc/mounts is changed). Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/dcache.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 50 insertions(+), 4 deletions(-) (limited to 'fs/dcache.c') diff --git a/fs/dcache.c b/fs/dcache.c index 7fccb00f498d..166d35d56868 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2019,6 +2019,11 @@ static int path_with_deleted(const struct path *path, struct path *root, return prepend_path(path, root, buf, buflen); } +static int prepend_unreachable(char **buffer, int *buflen) +{ + return prepend(buffer, buflen, "(unreachable)", 13); +} + /** * d_path - return the path of a dentry * @path: path to report @@ -2064,6 +2069,39 @@ char *d_path(const struct path *path, char *buf, int buflen) } EXPORT_SYMBOL(d_path); +/** + * d_path_with_unreachable - return the path of a dentry + * @path: path to report + * @buf: buffer to return value in + * @buflen: buffer length + * + * The difference from d_path() is that this prepends "(unreachable)" + * to paths which are unreachable from the current process' root. + */ +char *d_path_with_unreachable(const struct path *path, char *buf, int buflen) +{ + char *res = buf + buflen; + struct path root; + struct path tmp; + int error; + + if (path->dentry->d_op && path->dentry->d_op->d_dname) + return path->dentry->d_op->d_dname(path->dentry, buf, buflen); + + get_fs_root(current->fs, &root); + spin_lock(&dcache_lock); + tmp = root; + error = path_with_deleted(path, &tmp, &res, &buflen); + if (!error && !path_equal(&tmp, &root)) + error = prepend_unreachable(&res, &buflen); + spin_unlock(&dcache_lock); + path_put(&root); + if (error) + res = ERR_PTR(error); + + return res; +} + /* * Helper function for dentry_operations.d_dname() members */ @@ -2173,15 +2211,23 @@ SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) if (!d_unlinked(pwd.dentry)) { unsigned long len; struct path tmp = root; - char * cwd; + char *cwd = page + PAGE_SIZE; + int buflen = PAGE_SIZE; - cwd = __d_path(&pwd, &tmp, page, PAGE_SIZE); + prepend(&cwd, &buflen, "\0", 1); + error = prepend_path(&pwd, &tmp, &cwd, &buflen); spin_unlock(&dcache_lock); - error = PTR_ERR(cwd); - if (IS_ERR(cwd)) + if (error) goto out; + /* Unreachable from current root */ + if (!path_equal(&tmp, &root)) { + error = prepend_unreachable(&cwd, &buflen); + if (error) + goto out; + } + error = -ERANGE; len = PAGE_SIZE + page - cwd; if (len <= size) { -- cgit v1.2.2