At some point someone wrote sysfs_readdir to insert a cursor into the list of sysfs_dirents to ensure that sysfs_readdir would restart properly. That works but it is complex code and tends to be expensive. The same effect can be achived by keeping the sysfs_dirents in inode order and using the inode number as the f_pos. Then when we restart we just have to find the first dirent whose inode number is equal or greater then the last sysfs_dirent we attempted to return. Removing the sysfs directory cursor also allows the removal of all of the mysterious checks for sysfs_type(sd) != 0. Which were nonbovious checks to see if a cursor was in a directory list. Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx> --- fs/sysfs/dir.c | 178 ++++++++++++++---------------------------------------- fs/sysfs/inode.c | 2 - 2 files changed, 45 insertions(+), 135 deletions(-) diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index 1611cbd..f9be856 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -35,10 +35,20 @@ static void sysfs_attach_dentry(struct sysfs_dirent *sd, struct dentry *dentry); void sysfs_link_sibling(struct sysfs_dirent *sd) { struct sysfs_dirent *parent_sd = sd->s_parent; + struct sysfs_dirent **pos; BUG_ON(sd->s_sibling); - sd->s_sibling = parent_sd->s_children; - parent_sd->s_children = sd; + + /* Store directory entries in order by ino. This allows + * readdir to properly restart without having to add a + * cursor into the s_children list. + */ + for (pos = &parent_sd->s_children; *pos; pos = &(*pos)->s_sibling) { + if (sd->s_ino < (*pos)->s_ino) + break; + } + sd->s_sibling = *pos; + *pos = sd; } /** @@ -590,7 +600,7 @@ struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd, struct sysfs_dirent *sd; for (sd = parent_sd->s_children; sd; sd = sd->s_sibling) - if (sysfs_type(sd) && !strcmp(sd->s_name, name)) + if (!strcmp(sd->s_name, name)) return sd; return NULL; } @@ -696,8 +706,7 @@ static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry, goto out; for (sd = parent_sd->s_children; sd; sd = sd->s_sibling) { - if (sysfs_type(sd) && - !strcmp(sd->s_name, dentry->d_name.name)) + if (!strcmp(sd->s_name, dentry->d_name.name)) break; } @@ -756,7 +765,7 @@ static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd) while (*pos) { struct sysfs_dirent *sd = *pos; - if (sysfs_type(sd) && sysfs_type(sd) != SYSFS_DIR) { + if (sysfs_type(sd) != SYSFS_DIR) { *pos = sd->s_sibling; sd->s_sibling = NULL; sysfs_remove_one(&acxt, sd); @@ -913,37 +922,6 @@ again: return error; } -static int sysfs_dir_open(struct inode *inode, struct file *file) -{ - struct dentry * dentry = file->f_path.dentry; - struct sysfs_dirent * parent_sd = dentry->d_fsdata; - struct sysfs_dirent * sd; - - sd = sysfs_new_dirent("_DIR_", 0, 0); - if (sd) { - mutex_lock(&sysfs_mutex); - sd->s_parent = sysfs_get(parent_sd); - sysfs_link_sibling(sd); - mutex_unlock(&sysfs_mutex); - } - - file->private_data = sd; - return sd ? 0 : -ENOMEM; -} - -static int sysfs_dir_close(struct inode *inode, struct file *file) -{ - struct sysfs_dirent * cursor = file->private_data; - - mutex_lock(&sysfs_mutex); - sysfs_unlink_sibling(cursor); - mutex_unlock(&sysfs_mutex); - - release_sysfs_dirent(cursor); - - return 0; -} - /* Relationship between s_mode and the DT_xxx types */ static inline unsigned char dt_type(struct sysfs_dirent *sd) { @@ -954,117 +932,51 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir) { struct dentry *dentry = filp->f_path.dentry; struct sysfs_dirent * parent_sd = dentry->d_fsdata; - struct sysfs_dirent *cursor = filp->private_data; - struct sysfs_dirent **pos; + struct sysfs_dirent *pos; ino_t ino; - int i = filp->f_pos; - switch (i) { - case 0: - ino = parent_sd->s_ino; - if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0) - break; + if (filp->f_pos == 0) { + ino = parent_sd->s_ino; + if (filldir(dirent, ".", 1, filp->f_pos, ino, DT_DIR) == 0) filp->f_pos++; - i++; - /* fallthrough */ - case 1: - if (parent_sd->s_parent) - ino = parent_sd->s_parent->s_ino; - else - ino = parent_sd->s_ino; - if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0) - break; + } + if (filp->f_pos == 1) { + if (parent_sd->s_parent) + ino = parent_sd->s_parent->s_ino; + else + ino = parent_sd->s_ino; + if (filldir(dirent, "..", 2, filp->f_pos, ino, DT_DIR) == 0) filp->f_pos++; - i++; - /* fallthrough */ - default: - mutex_lock(&sysfs_mutex); - - pos = &parent_sd->s_children; - while (*pos != cursor) - pos = &(*pos)->s_sibling; - - /* unlink cursor */ - *pos = cursor->s_sibling; - - if (filp->f_pos == 2) - pos = &parent_sd->s_children; - - for ( ; *pos; pos = &(*pos)->s_sibling) { - struct sysfs_dirent *next = *pos; - const char * name; - int len; - - if (!sysfs_type(next)) - continue; - - name = next->s_name; - len = strlen(name); - ino = next->s_ino; - - if (filldir(dirent, name, len, filp->f_pos, ino, - dt_type(next)) < 0) - break; - - filp->f_pos++; - } + } + if ((filp->f_pos > 1) && (filp->f_pos < UINT_MAX)) { + mutex_lock(&sysfs_mutex); - /* put cursor back in */ - cursor->s_sibling = *pos; - *pos = cursor; + /* Skip the dentries we have already reported */ + pos = parent_sd->s_children; + while (pos && (filp->f_pos > pos->s_ino)) + pos = pos->s_sibling; - mutex_unlock(&sysfs_mutex); - } - return 0; -} + for ( ; pos; pos = pos->s_sibling) { + const char * name; + int len; -static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin) -{ - struct dentry * dentry = file->f_path.dentry; + name = pos->s_name; + len = strlen(name); + filp->f_pos = ino = pos->s_ino; - switch (origin) { - case 1: - offset += file->f_pos; - case 0: - if (offset >= 0) + if (filldir(dirent, name, len, filp->f_pos, ino, + dt_type(pos)) < 0) break; - default: - return -EINVAL; - } - if (offset != file->f_pos) { - mutex_lock(&sysfs_mutex); - - file->f_pos = offset; - if (file->f_pos >= 2) { - struct sysfs_dirent *sd = dentry->d_fsdata; - struct sysfs_dirent *cursor = file->private_data; - struct sysfs_dirent **pos; - loff_t n = file->f_pos - 2; - - sysfs_unlink_sibling(cursor); - - pos = &sd->s_children; - while (n && *pos) { - struct sysfs_dirent *next = *pos; - if (sysfs_type(next)) - n--; - pos = &(*pos)->s_sibling; - } - - cursor->s_sibling = *pos; - *pos = cursor; } - + if (!pos) + filp->f_pos = UINT_MAX; mutex_unlock(&sysfs_mutex); } - - return offset; + return 0; } + const struct file_operations sysfs_dir_operations = { - .open = sysfs_dir_open, - .release = sysfs_dir_close, - .llseek = sysfs_dir_lseek, .read = generic_read_dir, .readdir = sysfs_readdir, }; diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c index f55d9da..e212c69 100644 --- a/fs/sysfs/inode.c +++ b/fs/sysfs/inode.c @@ -225,8 +225,6 @@ int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name) for (pos = &dir_sd->s_children; *pos; pos = &(*pos)->s_sibling) { sd = *pos; - if (!sysfs_type(sd)) - continue; if (!strcmp(sd->s_name, name)) { *pos = sd->s_sibling; sd->s_sibling = NULL; -- 1.5.1.1.181.g2de0 _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers