mtd/ubi/ubi-media.h

4  * SPDX-License-Identifier:	GPL-2.0+
14  * This file defines the layout of UBI headers and all the other UBI on-flash
51  * @UBI_VTBL_AUTORESIZE_FLG: auto-resize this volume
53  * %UBI_VTBL_AUTORESIZE_FLG flag can be set only for one volume in the volume
54  * table. UBI automatically re-sizes the volume which has this flag and makes
55  * the volume to be of largest possible size. This means that if after the
57  * present on the device, it automatically appends all of them to the volume
65  * The auto-resize feature is useful for device production purposes. For
69  * exceed certain percent, e.g. 2%. When one creates an UBI image which will be
70  * flashed to the end devices in production, he does not know the exact amount
72  * number is required to calculate the volume sized and put them to the volume
73  * table of the UBI image. In this case, one of the volumes (e.g., the one
74  * which will store the root file system) is marked as "auto-resizable", and
78  * eraseblock handling, and then re-sizes the volume, not vice-versa. This
89  *                     to the flash
90  * @UBI_COMPAT_RO: attach this device in read-only mode
91  * @UBI_COMPAT_PRESERVE: preserve this internal volume - do not touch its
92  *                       physical eraseblocks, don't allow the wear-leveling
93  *                       sub-system to move them
108 #define UBI_EC_HDR_SIZE_CRC  (UBI_EC_HDR_SIZE  - sizeof(__be32))
109 #define UBI_VID_HDR_SIZE_CRC (UBI_VID_HDR_SIZE - sizeof(__be32))
112  * struct ubi_ec_hdr - UBI erase counter header.
114  * @version: version of UBI implementation which is supposed to accept this
125  * future usage. The unused fields are zeroed. The @version field is used to
126  * indicate the version of UBI implementation which is supposed to be able to
133  * volume identifier header and user data, relative to the beginning of the
134  * physical eraseblock. These values have to be the same for all physical
137  * The @image_seq field is used to validate a UBI image that has been prepared
141  * One way to make use of @image_seq is to increase its value by one every time
149 	__be64  ec; /* Warning: the current limit is 31-bit anyway! */
158  * struct ubi_vid_hdr - on-flash UBI volume identifier header.
160  * @version: UBI implementation version which is supposed to accept this UBI
164  *             eraseblock (for wear-leveling reasons)
170  * @data_size: how many bytes of data this logical eraseblock contains
172  * @data_pad: how many bytes at the end of this physical eraseblock are not
182  * UBI writes a new VID header to the flash, i.e. when it maps a logical
183  * eraseblock to a new physical eraseblock. The global sequence counter is an
184  * unsigned 64-bit integer and we assume it never overflows. The @sqnum
185  * (sequence number) is used to distinguish between older and newer versions of
188  * There are 2 situations when there may be more than one physical eraseblock
189  * corresponding to the same logical eraseblock, i.e., having the same @vol_id
191  * eraseblock L and it is mapped to the physical eraseblock P.
195  * erasure, then L is written to,i.e. mapped to another physical eraseblock P1,
196  * so P1 is written to, then an unclean reboot happens. Result - there are 2
197  * physical eraseblocks P and P1 corresponding to the same logical eraseblock
201  * 2. From time to time UBI moves logical eraseblocks to other physical
202  * eraseblocks for wear-leveling reasons. If, for example, UBI moves L from P
203  * to P1, and an unclean reboot happens before P is physically erased, there
204  * are two physical eraseblocks P and P1 corresponding to L and UBI has to
205  * select one of them when the flash is attached. The @sqnum field says which
207  * it is not enough to select the physical eraseblock with the higher sequence
209  * copying process, so the data in P is corrupted. It is also not enough to
211  * data there may be old (consider a case if more data was added to P1 after
216  * UBI uses the @copy_flag field to indicate that this logical eraseblock is a
218  * the @data_crc field of the copy (P1). So when UBI needs to pick one physical
219  * eraseblock of two (P or P1), the @copy_flag of the newer one (P1) is
220  * examined. If it is cleared, the situation* is simple and the newer one is
223  * the older one (P) is selected.
227  * UBI purposes. In this implementation there is only one internal volume - the
229  * For example, in future one may introduce a journal internal volume. Internal
234  * provides a mechanism to introduce UBI extensions and to be still compatible
239  * fine. This is similar to what Ext2fs does when it is fed by an Ext3fs image
240  * - it just ignores the Ext3fs journal.
245  * data of the physical eraseblock was moved by the wear-leveling sub-system,
246  * then the wear-leveling sub-system calculates the data CRC and stores it in
249  * The @data_size field is used only for static volumes because UBI has to know
250  * how many bytes of data are stored in this eraseblock. For dynamic volumes,
252  * physical eraseblock was moved to another physical eraseblock for
253  * wear-leveling reasons. In this case, UBI calculates CRC checksum of the
257  * The @used_ebs field is used only for static volumes and indicates how many
263  * eraseblocks of this volume. This is very handy when one uses block-oriented
292 #define UBI_INTERNAL_VOL_START (0x7FFFFFFF - 4096)
303 /* The maximum number of volumes per one UBI device */
313 #define UBI_VTBL_RECORD_SIZE_CRC (UBI_VTBL_RECORD_SIZE - sizeof(__be32))
316  * struct ubi_vtbl_record - a record in the volume table.
317  * @reserved_pebs: how many physical eraseblocks are reserved for this volume
319  * @data_pad: how many bytes are unused at the end of the each physical
320  * eraseblock to satisfy the requested alignment
335  * If the size of the logical eraseblock is large enough to fit
337  * records. Otherwise, it contains as many records as it can fit (i.e., size of
340  * The @upd_marker flag is used to implement volume update. It is set to %1
341  * before update and set to %0 after the update. So if the update operation was
345  * later changed. It may be useful, for example, when a block-oriented file
347  * logical eraseblock size and @alignment. The alignment must be multiple to the
370 /* UBI fastmap on-flash data structures */
375 /* fastmap on-flash data structure format version */
388 /* A fastmap can use up to UBI_FM_MAX_BLOCKS PEBs */
391 /* 5% of the total number of PEBs have to be scanned while attaching
393  * But the size of this pool is limited to be between UBI_FM_MIN_POOL_SIZE and
399  * struct ubi_fm_sb - UBI fastmap super block
422  * struct ubi_fm_hdr - header of the fastmap data set
426  * @scrub_peb_count: number of to be scrubbed PEBs known by this fastmap
428  * @erase_peb_count: number of bad PEBs which have to be erased
445  * struct ubi_fm_scan_pool - Fastmap pool PEBs to be scanned while attaching
462  * struct ubi_fm_ec - stores the erase counter of a PEB
472  * struct ubi_fm_volhdr - Fastmap volume header
492 /* struct ubi_fm_volhdr is followed by one struct ubi_fm_eba records */
495  * struct ubi_fm_eba - denotes an association beween a PEB and LEB