UBI: amend comments after all the renamings
This patch amends commentaries in scan.[ch] to match the new logic. Reminder - we did the restructuring to prepare the code for adding the fastmap. This patch also renames a couple of functions - it was too difficult to separate out that change and I decided that it is not too bad to have it in the same patch with commentaries changes. Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
This commit is contained in:
Artem Bityutskiy
Родитель
1fc2e3e59d
Коммит
fbd0107f4d
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@ -27,10 +27,6 @@
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* module load parameters or the kernel boot parameters. If MTD devices were
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* specified, UBI does not attach any MTD device, but it is possible to do
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* later using the "UBI control device".
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*
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* At the moment we only attach UBI devices by scanning, which will become a
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* bottleneck when flashes reach certain large size. Then one may improve UBI
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* and add other methods, although it does not seem to be easy to do.
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*/
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#include <linux/err.h>
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@ -790,11 +786,11 @@ static int io_init(struct ubi_device *ubi)
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ubi_msg("data offset: %d", ubi->leb_start);
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/*
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* Note, ideally, we have to initialize ubi->bad_peb_count here. But
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* Note, ideally, we have to initialize @ubi->bad_peb_count here. But
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* unfortunately, MTD does not provide this information. We should loop
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* over all physical eraseblocks and invoke mtd->block_is_bad() for
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* each physical eraseblock. So, we skip ubi->bad_peb_count
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* uninitialized and initialize it after scanning.
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* each physical eraseblock. So, we leave @ubi->bad_peb_count
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* uninitialized so far.
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*/
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return 0;
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@ -805,7 +801,7 @@ static int io_init(struct ubi_device *ubi)
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* @ubi: UBI device description object
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* @vol_id: ID of the volume to re-size
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*
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* This function re-sizes the volume marked by the @UBI_VTBL_AUTORESIZE_FLG in
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* This function re-sizes the volume marked by the %UBI_VTBL_AUTORESIZE_FLG in
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* the volume table to the largest possible size. See comments in ubi-header.h
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* for more description of the flag. Returns zero in case of success and a
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* negative error code in case of failure.
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@ -513,8 +513,7 @@ static int nor_erase_prepare(struct ubi_device *ubi, int pnum)
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* It is important to first invalidate the EC header, and then the VID
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* header. Otherwise a power cut may lead to valid EC header and
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* invalid VID header, in which case UBI will treat this PEB as
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* corrupted and will try to preserve it, and print scary warnings (see
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* the header comment in scan.c for more information).
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* corrupted and will try to preserve it, and print scary warnings.
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*/
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addr = (loff_t)pnum * ubi->peb_size;
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err = mtd_write(ubi->mtd, addr, 4, &written, (void *)&data);
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@ -19,21 +19,21 @@
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*/
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/*
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* UBI scanning sub-system.
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* UBI attaching sub-system.
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*
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* This sub-system is responsible for scanning the flash media, checking UBI
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* headers and providing complete information about the UBI flash image.
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* This sub-system is responsible for attaching MTD devices and it also
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* implements flash media scanning.
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*
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* The attaching information is represented by a &struct ubi_attach_info'
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* object. Information about found volumes is represented by
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* &struct ubi_ainf_volume objects which are kept in volume RB-tree with root
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* at the @volumes field. The RB-tree is indexed by the volume ID.
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* object. Information about volumes is represented by &struct ubi_ainf_volume
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* objects which are kept in volume RB-tree with root at the @volumes field.
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* The RB-tree is indexed by the volume ID.
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*
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* Scanned logical eraseblocks are represented by &struct ubi_ainf_peb objects.
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* These objects are kept in per-volume RB-trees with the root at the
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* corresponding &struct ubi_ainf_volume object. To put it differently, we keep
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* an RB-tree of per-volume objects and each of these objects is the root of
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* RB-tree of per-eraseblock objects.
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* Logical eraseblocks are represented by &struct ubi_ainf_peb objects. These
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* objects are kept in per-volume RB-trees with the root at the corresponding
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* &struct ubi_ainf_volume object. To put it differently, we keep an RB-tree of
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* per-volume objects and each of these objects is the root of RB-tree of
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* per-LEB objects.
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*
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* Corrupted physical eraseblocks are put to the @corr list, free physical
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* eraseblocks are put to the @free list and the physical eraseblock to be
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@ -51,28 +51,29 @@
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*
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* 1. Corruptions caused by power cuts. These are expected corruptions and UBI
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* tries to handle them gracefully, without printing too many warnings and
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* error messages. The idea is that we do not lose important data in these case
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* - we may lose only the data which was being written to the media just before
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* the power cut happened, and the upper layers (e.g., UBIFS) are supposed to
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* handle such data losses (e.g., by using the FS journal).
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* error messages. The idea is that we do not lose important data in these
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* cases - we may lose only the data which were being written to the media just
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* before the power cut happened, and the upper layers (e.g., UBIFS) are
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* supposed to handle such data losses (e.g., by using the FS journal).
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*
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* When UBI detects a corruption (CRC-32 mismatch) in a PEB, and it looks like
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* the reason is a power cut, UBI puts this PEB to the @erase list, and all
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* PEBs in the @erase list are scheduled for erasure later.
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*
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* 2. Unexpected corruptions which are not caused by power cuts. During
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* scanning, such PEBs are put to the @corr list and UBI preserves them.
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* attaching, such PEBs are put to the @corr list and UBI preserves them.
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* Obviously, this lessens the amount of available PEBs, and if at some point
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* UBI runs out of free PEBs, it switches to R/O mode. UBI also loudly informs
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* about such PEBs every time the MTD device is attached.
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*
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* However, it is difficult to reliably distinguish between these types of
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* corruptions and UBI's strategy is as follows. UBI assumes corruption type 2
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* if the VID header is corrupted and the data area does not contain all 0xFFs,
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* and there were no bit-flips or integrity errors while reading the data area.
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* Otherwise UBI assumes corruption type 1. So the decision criteria are as
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* follows.
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* o If the data area contains only 0xFFs, there is no data, and it is safe
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* corruptions and UBI's strategy is as follows (in case of attaching by
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* scanning). UBI assumes corruption type 2 if the VID header is corrupted and
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* the data area does not contain all 0xFFs, and there were no bit-flips or
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* integrity errors (e.g., ECC errors in case of NAND) while reading the data
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* area. Otherwise UBI assumes corruption type 1. So the decision criteria
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* are as follows.
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* o If the data area contains only 0xFFs, there are no data, and it is safe
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* to just erase this PEB - this is corruption type 1.
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* o If the data area has bit-flips or data integrity errors (ECC errors on
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* NAND), it is probably a PEB which was being erased when power cut
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@ -102,7 +103,8 @@ static struct ubi_vid_hdr *vidh;
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* @to_head: if not zero, add to the head of the list
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* @list: the list to add to
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*
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* This function adds physical eraseblock @pnum to free, erase, or alien lists.
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* This function allocates a 'struct ubi_ainf_peb' object for physical
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* eraseblock @pnum and adds it to the "free", "erase", or "alien" lists.
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* If @to_head is not zero, PEB will be added to the head of the list, which
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* basically means it will be processed first later. E.g., we add corrupted
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* PEBs (corrupted due to power cuts) to the head of the erase list to make
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@ -144,9 +146,10 @@ static int add_to_list(struct ubi_attach_info *ai, int pnum, int ec,
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* @pnum: physical eraseblock number to add
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* @ec: erase counter of the physical eraseblock
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*
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* This function adds corrupted physical eraseblock @pnum to the 'corr' list.
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* The corruption was presumably not caused by a power cut. Returns zero in
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* case of success and a negative error code in case of failure.
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* This function allocates a 'struct ubi_ainf_peb' object for a corrupted
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* physical eraseblock @pnum and adds it to the 'corr' list. The corruption
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* was presumably not caused by a power cut. Returns zero in case of success
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* and a negative error code in case of failure.
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*/
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static int add_corrupted(struct ubi_attach_info *ai, int pnum, int ec)
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{
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@ -241,8 +244,8 @@ bad:
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* If the volume corresponding to the @vid_hdr logical eraseblock is already
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* present in the attaching information, this function does nothing. Otherwise
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* it adds corresponding volume to the attaching information. Returns a pointer
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* to the scanning volume object in case of success and a negative error code
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* in case of failure.
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* to the allocated "av" object 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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static struct ubi_ainf_volume *add_volume(struct ubi_attach_info *ai,
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int vol_id, int pnum,
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@ -425,7 +428,7 @@ out_free_vidh:
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}
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/**
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* ubi_add_to_av - add physical eraseblock to the attaching information.
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* ubi_add_to_av - add used physical eraseblock to the attaching information.
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* @ubi: UBI device description object
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* @ai: attaching information
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* @pnum: the physical eraseblock number
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@ -692,8 +695,8 @@ out_free:
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* the lists, writes the EC header if it is needed, and removes it from the
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* list.
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*
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* This function returns scanning physical eraseblock information in case of
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* success and an error code in case of failure.
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* This function returns a pointer to the "aeb" of the found free PEB in case
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* of success and an error code in case of failure.
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*/
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struct ubi_ainf_peb *ubi_early_get_peb(struct ubi_device *ubi,
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struct ubi_attach_info *ai)
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@ -793,16 +796,18 @@ out_unlock:
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}
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/**
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* process_eb - read, check UBI headers, and add them to attaching information.
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* scan_peb - scan and process UBI headers of a PEB.
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* @ubi: UBI device description object
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* @ai: attaching information
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* @pnum: the physical eraseblock number
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*
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* This function returns a zero if the physical eraseblock was successfully
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* handled and a negative error code in case of failure.
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* This function reads UBI headers of PEB @pnum, checks them, and adds
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* information about this PEB to the corresponding list or RB-tree in the
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* "attaching info" structure. Returns zero if the physical eraseblock was
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* successfully handled and a negative error code in case of failure.
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*/
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static int process_eb(struct ubi_device *ubi, struct ubi_attach_info *ai,
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int pnum)
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static int scan_peb(struct ubi_device *ubi, struct ubi_attach_info *ai,
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int pnum)
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{
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long long uninitialized_var(ec);
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int err, bitflips = 0, vol_id, ec_err = 0;
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@ -814,11 +819,6 @@ static int process_eb(struct ubi_device *ubi, struct ubi_attach_info *ai,
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if (err < 0)
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return err;
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else if (err) {
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/*
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* FIXME: this is actually duty of the I/O sub-system to
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* initialize this, but MTD does not provide enough
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* information.
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*/
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ai->bad_peb_count += 1;
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return 0;
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}
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@ -1033,18 +1033,17 @@ adjust_mean_ec:
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}
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/**
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* check_what_we_have - check what PEB were found by scanning.
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* late_analysis - analyze the overall situation with PEB.
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* @ubi: UBI device description object
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* @ai: attaching information
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*
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* This is a helper function which takes a look what PEBs were found by
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* scanning, and decides whether the flash is empty and should be formatted and
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* whether there are too many corrupted PEBs and we should not attach this
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* MTD device. Returns zero if we should proceed with attaching the MTD device,
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* and %-EINVAL if we should not.
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* This is a helper function which takes a look what PEBs we have after we
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* gather information about all of them ("ai" is compete). It decides whether
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* the flash is empty and should be formatted of whether there are too many
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* corrupted PEBs and we should not attach this MTD device. Returns zero if we
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* should proceed with attaching the MTD device, and %-EINVAL if we should not.
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*/
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static int check_what_we_have(struct ubi_device *ubi,
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struct ubi_attach_info *ai)
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static int late_analysis(struct ubi_device *ubi, struct ubi_attach_info *ai)
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{
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struct ubi_ainf_peb *aeb;
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int max_corr, peb_count;
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@ -1112,7 +1111,8 @@ static int check_what_we_have(struct ubi_device *ubi,
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* @ubi: UBI device description object
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*
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* This function does full scanning of an MTD device and returns complete
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* information about it. In case of failure, an error code is returned.
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* information about it in form of a "struct ubi_attach_info" object. In case
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* of failure, an error code is returned.
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*/
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struct ubi_attach_info *ubi_scan(struct ubi_device *ubi)
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{
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@ -1151,7 +1151,7 @@ struct ubi_attach_info *ubi_scan(struct ubi_device *ubi)
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cond_resched();
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dbg_gen("process PEB %d", pnum);
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err = process_eb(ubi, ai, pnum);
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err = scan_peb(ubi, ai, pnum);
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if (err < 0)
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goto out_vidh;
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}
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@ -1162,7 +1162,7 @@ struct ubi_attach_info *ubi_scan(struct ubi_device *ubi)
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if (ai->ec_count)
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ai->mean_ec = div_u64(ai->ec_sum, ai->ec_count);
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err = check_what_we_have(ubi, ai);
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err = late_analysis(ubi, ai);
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if (err)
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goto out_vidh;
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@ -1208,12 +1208,11 @@ out_ai:
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}
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/**
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* destroy_av - free the scanning volume information
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* @av: scanning volume information
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* destroy_av - free volume attaching information.
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* @av: volume attaching information
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* @ai: attaching information
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*
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* This function destroys the volume RB-tree (@av->root) and the scanning
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* volume information.
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* This function destroys the volume attaching information.
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*/
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static void destroy_av(struct ubi_attach_info *ai, struct ubi_ainf_volume *av)
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{
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@ -146,7 +146,7 @@ struct ubi_vid_hdr;
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* ubi_move_aeb_to_list - move a PEB from the volume tree to a list.
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*
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* @av: volume attaching information
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* @aeb: scanning eraseblock information
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* @aeb: attaching eraseblock information
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* @list: the list to move to
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*/
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static inline void ubi_move_aeb_to_list(struct ubi_ainf_volume *av,
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@ -149,10 +149,10 @@ enum {
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* The @image_seq field is used to validate a UBI image that has been prepared
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* for a UBI device. The @image_seq value can be any value, but it must be the
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* same on all eraseblocks. UBI will ensure that all new erase counter headers
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* also contain this value, and will check the value when scanning at start-up.
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* also contain this value, and will check the value when attaching the flash.
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* One way to make use of @image_seq is to increase its value by one every time
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* an image is flashed over an existing image, then, if the flashing does not
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* complete, UBI will detect the error when scanning.
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* complete, UBI will detect the error when attaching the media.
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*/
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struct ubi_ec_hdr {
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__be32 magic;
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|
|
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@ -37,16 +37,15 @@
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* LEB 1. This scheme guarantees recoverability from unclean reboots.
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*
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* In this UBI implementation the on-flash volume table does not contain any
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* information about how many data static volumes contain. This information may
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* be found from the scanning data.
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* information about how much data static volumes contain.
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*
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* But it would still be beneficial to store this information in the volume
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* table. For example, suppose we have a static volume X, and all its physical
|
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* eraseblocks became bad for some reasons. Suppose we are attaching the
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* corresponding MTD device, the scanning has found no logical eraseblocks
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* corresponding MTD device, for some reason we find no logical eraseblocks
|
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* corresponding to the volume X. According to the volume table volume X does
|
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* exist. So we don't know whether it is just empty or all its physical
|
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* eraseblocks went bad. So we cannot alarm the user about this corruption.
|
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* eraseblocks went bad. So we cannot alarm the user properly.
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*
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* The volume table also stores so-called "update marker", which is used for
|
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* volume updates. Before updating the volume, the update marker is set, and
|
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|
|
@ -702,16 +701,16 @@ bad:
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}
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/**
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* check_scanning_info - check that attaching information.
|
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* check_attaching_info - check that attaching information.
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* @ubi: UBI device description object
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* @ai: attaching information
|
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*
|
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* Even though we protect on-flash data by CRC checksums, we still don't trust
|
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* the media. This function ensures that attaching information is consistent to
|
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* the information read from the volume table. Returns zero if the scanning
|
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* the information read from the volume table. Returns zero if the attaching
|
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* information is OK and %-EINVAL if it is not.
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*/
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static int check_scanning_info(const struct ubi_device *ubi,
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static int check_attaching_info(const struct ubi_device *ubi,
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struct ubi_attach_info *ai)
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{
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int err, i;
|
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|
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@ -719,15 +718,14 @@ static int check_scanning_info(const struct ubi_device *ubi,
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struct ubi_volume *vol;
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if (ai->vols_found > UBI_INT_VOL_COUNT + ubi->vtbl_slots) {
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ubi_err("scanning found %d volumes, maximum is %d + %d",
|
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ubi_err("found %d volumes while attaching, maximum is %d + %d",
|
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ai->vols_found, UBI_INT_VOL_COUNT, ubi->vtbl_slots);
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return -EINVAL;
|
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}
|
||||
|
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if (ai->highest_vol_id >= ubi->vtbl_slots + UBI_INT_VOL_COUNT &&
|
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ai->highest_vol_id < UBI_INTERNAL_VOL_START) {
|
||||
ubi_err("too large volume ID %d found by scanning",
|
||||
ai->highest_vol_id);
|
||||
ubi_err("too large volume ID %d found", ai->highest_vol_id);
|
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return -EINVAL;
|
||||
}
|
||||
|
||||
|
|
@ -749,7 +747,7 @@ static int check_scanning_info(const struct ubi_device *ubi,
|
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continue;
|
||||
|
||||
/*
|
||||
* During scanning we found a volume which does not
|
||||
* During attaching we found a volume which does not
|
||||
* exist according to the information in the volume
|
||||
* table. This must have happened due to an unclean
|
||||
* reboot while the volume was being removed. Discard
|
||||
|
|
@ -839,7 +837,7 @@ int ubi_read_volume_table(struct ubi_device *ubi, struct ubi_attach_info *ai)
|
|||
* Make sure that the attaching information is consistent to the
|
||||
* information stored in the volume table.
|
||||
*/
|
||||
err = check_scanning_info(ubi, ai);
|
||||
err = check_attaching_info(ubi, ai);
|
||||
if (err)
|
||||
goto out_free;
|
||||
|
||||
|
|
|
|||
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