UBI: introduce volume refcounting
Add ref_count field to UBI volumes and remove weired "vol->removed" field. This way things are better understandable and we do not have to do whold show_attr operation under spinlock. Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
This commit is contained in:
Artem Bityutskiy
parent
db6e5770ef
commit
d05c77a816
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@ -301,6 +301,8 @@ int ubi_eba_unmap_leb(struct ubi_device *ubi, struct ubi_volume *vol,
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{
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int err, pnum, vol_id = vol->vol_id;
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ubi_assert(vol->ref_count > 0);
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if (ubi->ro_mode)
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return -EROFS;
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@ -349,6 +351,8 @@ int ubi_eba_read_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
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struct ubi_vid_hdr *vid_hdr;
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uint32_t uninitialized_var(crc);
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ubi_assert(vol->ref_count > 0);
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err = leb_read_lock(ubi, vol_id, lnum);
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if (err)
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return err;
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@ -572,6 +576,8 @@ int ubi_eba_write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
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int err, pnum, tries = 0, vol_id = vol->vol_id;
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struct ubi_vid_hdr *vid_hdr;
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ubi_assert(vol->ref_count > 0);
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if (ubi->ro_mode)
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return -EROFS;
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@ -705,6 +711,8 @@ int ubi_eba_write_leb_st(struct ubi_device *ubi, struct ubi_volume *vol,
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struct ubi_vid_hdr *vid_hdr;
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uint32_t crc;
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ubi_assert(vol->ref_count > 0);
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if (ubi->ro_mode)
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return -EROFS;
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@ -819,6 +827,8 @@ int ubi_eba_atomic_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
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struct ubi_vid_hdr *vid_hdr;
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uint32_t crc;
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ubi_assert(vol->ref_count > 0);
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if (ubi->ro_mode)
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return -EROFS;
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@ -152,6 +152,7 @@ struct ubi_volume_desc *ubi_open_volume(int ubi_num, int vol_id, int mode)
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break;
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}
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get_device(&vol->dev);
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vol->ref_count += 1;
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spin_unlock(&ubi->volumes_lock);
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desc->vol = vol;
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@ -261,10 +262,11 @@ void ubi_close_volume(struct ubi_volume_desc *desc)
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case UBI_EXCLUSIVE:
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vol->exclusive = 0;
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}
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vol->ref_count -= 1;
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spin_unlock(&vol->ubi->volumes_lock);
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kfree(desc);
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put_device(&vol->dev);
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kfree(desc);
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module_put(THIS_MODULE);
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}
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EXPORT_SYMBOL_GPL(ubi_close_volume);
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@ -140,10 +140,10 @@ struct ubi_volume_desc;
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* @cdev: character device object to create character device
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* @ubi: reference to the UBI device description object
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* @vol_id: volume ID
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* @ref_count: volume reference count
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* @readers: number of users holding this volume in read-only mode
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* @writers: number of users holding this volume in read-write mode
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* @exclusive: whether somebody holds this volume in exclusive mode
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* @removed: if the volume was removed
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* @checked: if this static volume was checked
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*
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* @reserved_pebs: how many physical eraseblocks are reserved for this volume
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@ -156,7 +156,7 @@ struct ubi_volume_desc;
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* @corrupted: non-zero if the volume is corrupted (static volumes only)
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* @alignment: volume alignment
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* @data_pad: how many bytes are not used at the end of physical eraseblocks to
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* satisfy the requested alignment
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* satisfy the requested alignment
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* @name_len: volume name length
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* @name: volume name
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*
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@ -185,10 +185,10 @@ struct ubi_volume {
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struct cdev cdev;
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struct ubi_device *ubi;
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int vol_id;
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int ref_count;
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int readers;
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int writers;
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int exclusive;
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int removed;
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int checked;
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int reserved_pebs;
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@ -242,9 +242,9 @@ struct ubi_wl_entry;
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* @vol_count: number of volumes in this UBI device
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* @volumes: volumes of this UBI device
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* @volumes_lock: protects @volumes, @rsvd_pebs, @avail_pebs, beb_rsvd_pebs,
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* @beb_rsvd_level, @bad_peb_count, @good_peb_count, @vol_count, @vol->readers,
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* @vol->writers, @vol->exclusive, @vol->removed, @vol->mapping and
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* @vol->eba_tbl.
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* @beb_rsvd_level, @bad_peb_count, @good_peb_count, @vol_count,
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* @vol->readers, @vol->writers, @vol->exclusive,
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* @vol->ref_count, @vol->mapping and @vol->eba_tbl.
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*
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* @rsvd_pebs: count of reserved physical eraseblocks
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* @avail_pebs: count of available physical eraseblocks
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@ -273,11 +273,11 @@ struct ubi_wl_entry;
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* @prot.pnum: protection tree indexed by physical eraseblock numbers
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* @prot.aec: protection tree indexed by absolute erase counter value
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* @wl_lock: protects the @used, @free, @prot, @lookuptbl, @abs_ec, @move_from,
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* @move_to, @move_to_put @erase_pending, @wl_scheduled, and @works
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* fields
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* @move_to, @move_to_put @erase_pending, @wl_scheduled, and @works
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* fields
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* @wl_scheduled: non-zero if the wear-leveling was scheduled
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* @lookuptbl: a table to quickly find a &struct ubi_wl_entry object for any
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* physical eraseblock
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* physical eraseblock
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* @abs_ec: absolute erase counter
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* @move_from: physical eraseblock from where the data is being moved
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* @move_to: physical eraseblock where the data is being moved to
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@ -308,13 +308,13 @@ struct ubi_wl_entry;
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* @hdrs_min_io_size
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* @vid_hdr_shift: contains @vid_hdr_offset - @vid_hdr_aloffset
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* @bad_allowed: whether the MTD device admits of bad physical eraseblocks or
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* not
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* not
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* @mtd: MTD device descriptor
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*
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* @peb_buf1: a buffer of PEB size used for different purposes
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* @peb_buf2: another buffer of PEB size used for different purposes
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* @buf_mutex: proptects @peb_buf1 and @peb_buf2
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* @dbg_peb_buf: buffer of PEB size used for debugging
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* @dbg_peb_buf: buffer of PEB size used for debugging
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* @dbg_buf_mutex: proptects @dbg_peb_buf
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*/
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struct ubi_device {
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@ -63,21 +63,24 @@ static struct device_attribute attr_vol_upd_marker =
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* B. process 2 removes volume Y;
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* C. process 1 starts reading the /<sysfs>/class/ubi/ubiX_Y/reserved_ebs file;
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*
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* What we want to do in a situation like that is to return error when the file
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* is read. This is done by means of the 'removed' flag and the 'vol_lock' of
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* the UBI volume description object.
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* In this situation, this function will return %-ENODEV because it will find
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* out that the volume was removed from the @ubi->volumes array.
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*/
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static ssize_t vol_attribute_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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int ret = -ENODEV;
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int ret;
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struct ubi_volume *vol = container_of(dev, struct ubi_volume, dev);
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struct ubi_device *ubi = vol->ubi;
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spin_lock(&vol->ubi->volumes_lock);
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if (vol->removed) {
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spin_unlock(&vol->ubi->volumes_lock);
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return ret;
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spin_lock(&ubi->volumes_lock);
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if (!ubi->volumes[vol->vol_id]) {
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spin_unlock(&ubi->volumes_lock);
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return -ENODEV;
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}
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/* Take a reference to prevent volume removal */
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vol->ref_count += 1;
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spin_unlock(&ubi->volumes_lock);
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if (attr == &attr_vol_reserved_ebs)
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ret = sprintf(buf, "%d\n", vol->reserved_pebs);
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@ -102,8 +105,13 @@ static ssize_t vol_attribute_show(struct device *dev,
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else if (attr == &attr_vol_upd_marker)
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ret = sprintf(buf, "%d\n", vol->upd_marker);
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else
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BUG();
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spin_unlock(&vol->ubi->volumes_lock);
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/* This must be a bug */
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ret = -EINVAL;
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spin_lock(&ubi->volumes_lock);
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vol->ref_count -= 1;
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ubi_assert(vol->ref_count >= 0);
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spin_unlock(&ubi->volumes_lock);
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return ret;
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}
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@ -179,7 +187,7 @@ static void volume_sysfs_close(struct ubi_volume *vol)
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* @req: volume creation request
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*
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* This function creates volume described by @req. If @req->vol_id id
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* %UBI_VOL_NUM_AUTO, this function automatically assigne ID to the new volume
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* %UBI_VOL_NUM_AUTO, this function automatically assign ID to the new volume
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* and saves it in @req->vol_id. Returns zero in case of success and a negative
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* error code in case of failure.
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*/
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@ -261,7 +269,6 @@ int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req)
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memcpy(vol->name, req->name, vol->name_len + 1);
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vol->exclusive = 1;
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vol->ubi = ubi;
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ubi->volumes[vol_id] = vol;
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spin_unlock(&ubi->volumes_lock);
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/*
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@ -345,6 +352,7 @@ int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req)
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spin_lock(&ubi->volumes_lock);
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ubi->vol_count += 1;
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vol->exclusive = 0;
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ubi->volumes[vol_id] = vol;
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spin_unlock(&ubi->volumes_lock);
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paranoid_check_volumes(ubi);
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@ -353,7 +361,7 @@ int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req)
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out_sysfs:
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/*
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* We have degistered our device, we should not free the volume*
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* We have registered our device, we should not free the volume*
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* description object in this function in case of an error - it is
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* freed by the release function.
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*
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@ -373,7 +381,6 @@ out_acc:
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spin_lock(&ubi->volumes_lock);
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ubi->rsvd_pebs -= vol->reserved_pebs;
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ubi->avail_pebs += vol->reserved_pebs;
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ubi->volumes[vol_id] = NULL;
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out_unlock:
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spin_unlock(&ubi->volumes_lock);
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mutex_unlock(&ubi->volumes_mutex);
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@ -407,25 +414,32 @@ int ubi_remove_volume(struct ubi_volume_desc *desc)
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return -EROFS;
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mutex_lock(&ubi->volumes_mutex);
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spin_lock(&ubi->volumes_lock);
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if (vol->ref_count > 1) {
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/*
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* The volume is busy, probably someone is reading one of its
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* sysfs files.
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*/
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err = -EBUSY;
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goto out_unlock;
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}
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ubi->volumes[vol_id] = NULL;
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spin_unlock(&ubi->volumes_lock);
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err = ubi_destroy_gluebi(vol);
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if (err)
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goto out;
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goto out_err;
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err = ubi_change_vtbl_record(ubi, vol_id, NULL);
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if (err)
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goto out;
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goto out_err;
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for (i = 0; i < vol->reserved_pebs; i++) {
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err = ubi_eba_unmap_leb(ubi, vol, i);
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if (err)
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goto out;
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goto out_err;
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}
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spin_lock(&ubi->volumes_lock);
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vol->removed = 1;
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ubi->volumes[vol_id] = NULL;
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spin_unlock(&ubi->volumes_lock);
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kfree(vol->eba_tbl);
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vol->eba_tbl = NULL;
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cdev_del(&vol->cdev);
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@ -447,7 +461,15 @@ int ubi_remove_volume(struct ubi_volume_desc *desc)
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spin_unlock(&ubi->volumes_lock);
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paranoid_check_volumes(ubi);
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out:
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mutex_unlock(&ubi->volumes_mutex);
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return 0;
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out_err:
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ubi_err("cannot remove volume %d, error %d", vol_id, err);
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spin_lock(&ubi->volumes_lock);
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ubi->volumes[vol_id] = vol;
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out_unlock:
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spin_unlock(&ubi->volumes_lock);
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mutex_unlock(&ubi->volumes_mutex);
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return err;
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}
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@ -494,8 +516,17 @@ int ubi_resize_volume(struct ubi_volume_desc *desc, int reserved_pebs)
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for (i = 0; i < reserved_pebs; i++)
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new_mapping[i] = UBI_LEB_UNMAPPED;
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/* Reserve physical eraseblocks */
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mutex_lock(&ubi->volumes_mutex);
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spin_lock(&ubi->volumes_lock);
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if (vol->ref_count > 1) {
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spin_unlock(&ubi->volumes_lock);
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err = -EBUSY;
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goto out_free;
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}
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spin_unlock(&ubi->volumes_lock);
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/* Reserve physical eraseblocks */
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pebs = reserved_pebs - vol->reserved_pebs;
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if (pebs > 0) {
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spin_lock(&ubi->volumes_lock);
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@ -577,8 +608,8 @@ out_free:
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* @ubi: UBI device description object
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* @vol: volume description object
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*
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* This function adds an existin volume and initializes all its data
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* structures. Returnes zero in case of success and a negative error code in
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* This function adds an existing volume and initializes all its data
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* structures. Returns zero in case of success and a negative error code in
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* case of failure.
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*/
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int ubi_add_volume(struct ubi_device *ubi, struct ubi_volume *vol)
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@ -588,7 +619,6 @@ int ubi_add_volume(struct ubi_device *ubi, struct ubi_volume *vol)
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dbg_msg("add volume %d", vol_id);
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ubi_dbg_dump_vol_info(vol);
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ubi_assert(vol);
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/* Register character device for the volume */
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cdev_init(&vol->cdev, &ubi_vol_cdev_operations);
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@ -645,11 +675,9 @@ void ubi_free_volume(struct ubi_device *ubi, struct ubi_volume *vol)
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int err;
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dbg_msg("free volume %d", vol->vol_id);
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ubi_assert(vol);
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vol->removed = 1;
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err = ubi_destroy_gluebi(vol);
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ubi->volumes[vol->vol_id] = NULL;
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err = ubi_destroy_gluebi(vol);
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cdev_del(&vol->cdev);
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volume_sysfs_close(vol);
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}
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@ -565,6 +565,7 @@ static int init_volumes(struct ubi_device *ubi, const struct ubi_scan_info *si,
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vol->last_eb_bytes = sv->last_data_size;
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}
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/* And add the layout volume */
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vol = kzalloc(sizeof(struct ubi_volume), GFP_KERNEL);
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if (!vol)
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return -ENOMEM;
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@ -580,6 +581,7 @@ static int init_volumes(struct ubi_device *ubi, const struct ubi_scan_info *si,
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vol->used_bytes =
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(long long)vol->used_ebs * (ubi->leb_size - vol->data_pad);
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vol->vol_id = UBI_LAYOUT_VOL_ID;
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vol->ref_count = 1;
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ubi_assert(!ubi->volumes[i]);
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ubi->volumes[vol_id2idx(ubi, vol->vol_id)] = vol;
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