To match the previous patch which used the pre-alloc buffer for writes, this patch causes reads to use the same buffer. This is not strictly necessary as the current seq_read() will allocate on first read, so user-space can trigger the required pre-alloc. But consistency is valuable.
The read function is somewhat simpler than seq_read() and, for example, does not support reading from an offset into the file: reads must be at the start of the file. As the buffer is shared with writes and other reads, the mutex is extended to cover the copy_to_user. Signed-off-by: NeilBrown <[email protected]> --- fs/kernfs/file.c | 17 ++++++++++------- fs/sysfs/file.c | 28 ++++++++++++++++++++++++---- 2 files changed, 34 insertions(+), 11 deletions(-) diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c index 73bd5ed143cd..7072240604f5 100644 --- a/fs/kernfs/file.c +++ b/fs/kernfs/file.c @@ -189,7 +189,9 @@ static ssize_t kernfs_file_direct_read(struct kernfs_open_file *of, const struct kernfs_ops *ops; char *buf; - buf = kmalloc(len, GFP_KERNEL); + buf = of->buf; + if (!buf) + buf = kmalloc(len, GFP_KERNEL); if (!buf) return -ENOMEM; @@ -210,21 +212,22 @@ static ssize_t kernfs_file_direct_read(struct kernfs_open_file *of, else len = -EINVAL; - kernfs_put_active(of->kn); - mutex_unlock(&of->mutex); - if (len < 0) - goto out_free; + goto out_unlock; if (copy_to_user(user_buf, buf, len)) { len = -EFAULT; - goto out_free; + goto out_unlock; } *ppos += len; + out_unlock: + kernfs_put_active(of->kn); + mutex_unlock(&of->mutex); out_free: - kfree(buf); + if (buf != of->buf) + kfree(buf); return len; } diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index 4a959d231b43..3f7e4d341546 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -102,6 +102,18 @@ static ssize_t sysfs_kf_bin_read(struct kernfs_open_file *of, char *buf, return battr->read(of->file, kobj, battr, buf, pos, count); } +/* kernfs read callback for regular sysfs files with pre-alloc */ +static ssize_t sysfs_kf_read(struct kernfs_open_file *of, char *buf, + size_t count, loff_t pos) +{ + const struct sysfs_ops *ops = sysfs_file_ops(of->kn); + struct kobject *kobj = of->kn->parent->priv; + + if (pos) + return 0; + return ops->show(kobj, of->kn->priv, buf); +} + /* kernfs write callback for regular sysfs files */ static ssize_t sysfs_kf_write(struct kernfs_open_file *of, char *buf, size_t count, loff_t pos) @@ -184,13 +196,18 @@ static const struct kernfs_ops sysfs_file_kfops_rw = { .write = sysfs_kf_write, }; +static const struct kernfs_ops sysfs_prealloc_kfops_ro = { + .read = sysfs_kf_read, + .prealloc = true, +}; + static const struct kernfs_ops sysfs_prealloc_kfops_wo = { .write = sysfs_kf_write, .prealloc = true, }; static const struct kernfs_ops sysfs_prealloc_kfops_rw = { - .seq_show = sysfs_kf_seq_show, + .read = sysfs_kf_read, .write = sysfs_kf_write, .prealloc = true, }; @@ -238,9 +255,12 @@ int sysfs_add_file_mode_ns(struct kernfs_node *parent, ops = &sysfs_prealloc_kfops_rw; else ops = &sysfs_file_kfops_rw; - } else if (sysfs_ops->show) - ops = &sysfs_file_kfops_ro; - else if (sysfs_ops->store) { + } else if (sysfs_ops->show) { + if (mode & SYSFS_PREALLOC) + ops = &sysfs_prealloc_kfops_ro; + else + ops = &sysfs_file_kfops_ro; + } else if (sysfs_ops->store) { if (mode & SYSFS_PREALLOC) ops = &sysfs_prealloc_kfops_wo; else -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
