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UBI: handle more error codes

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The UBIFS WL worker may encounter read errors and there is logic
which makes a decision whether we should do one of:

1. cancel the operation and move the PEB with the read errors to
   the 'erroneous' list;
2. switch to R/O mode.

ATM, only -EIO errors trigger 1., other errors trigger 2. The idea
is that if we know we encountered an I/O error, do 1. Otherwise,
we do not know how to react, and do 2., just in case. E.g., if
the underlying driver became crazy because of a bug, we do not
want to harm any data, and switch to R/O mode.

This patch does 2 things:
1. Makes sure reads from the source PEB always cause 1. This is
   more consistent with other reads which come from the upper
   layers and never cause R/O.
2. Teaches UBI to do 1. also on -EBADMSG, UBI_IO_BAD_VID_HDR,
   -ENOMEM, and -ETIMEOUT. But this is only when reading the
   target PEB.

This preblems were hunted by Adrian Hunter.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
This commit is contained in:
Artem Bityutskiy 2009-06-10 11:32:05 +03:00
parent 815bc5f8fe
commit 6b5c94c6b4
1 changed files with 34 additions and 7 deletions
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41
drivers/mtd/ubi/eba.c
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@ -940,6 +940,33 @@ write_error:
goto retry;
}
/**
* is_error_sane - check whether a read error is sane.
* @err: code of the error happened during reading
*
* This is a helper function for 'ubi_eba_copy_leb()' which is called when we
* cannot read data from the target PEB (an error @err happened). If the error
* code is sane, then we treat this error as non-fatal. Otherwise the error is
* fatal and UBI will be switched to R/O mode later.
*
* The idea is that we try not to switch to R/O mode if the read error is
* something which suggests there was a real read problem. E.g., %-EIO. Or a
* memory allocation failed (-%ENOMEM). Otherwise, it is safer to switch to R/O
* mode, simply because we do not know what happened at the MTD level, and we
* cannot handle this. E.g., the underlying driver may have become crazy, and
* it is safer to switch to R/O mode to preserve the data.
*
* And bear in mind, this is about reading from the target PEB, i.e. the PEB
* which we have just written.
*/
static int is_error_sane(int err)
{
if (err == -EIO || err == -ENOMEM || err == UBI_IO_BAD_VID_HDR ||
err == -ETIMEDOUT)
return 0;
return 1;
}
/**
* ubi_eba_copy_leb - copy logical eraseblock.
* @ubi: UBI device description object
@ -1033,8 +1060,7 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
if (err && err != UBI_IO_BITFLIPS) {
ubi_warn("error %d while reading data from PEB %d",
err, from);
if (err == -EIO)
err = MOVE_SOURCE_RD_ERR;
err = MOVE_SOURCE_RD_ERR;
goto out_unlock_buf;
}
@ -1082,8 +1108,9 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
err = ubi_io_read_vid_hdr(ubi, to, vid_hdr, 1);
if (err) {
if (err != UBI_IO_BITFLIPS) {
ubi_warn("cannot read VID header back from PEB %d", to);
if (err == -EIO)
ubi_warn("error %d while reading VID header back from "
"PEB %d", err, to);
if (is_error_sane(err))
err = MOVE_TARGET_RD_ERR;
} else
err = MOVE_CANCEL_BITFLIPS;
@ -1108,9 +1135,9 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
err = ubi_io_read_data(ubi, ubi->peb_buf2, to, 0, aldata_size);
if (err) {
if (err != UBI_IO_BITFLIPS) {
ubi_warn("cannot read data back from PEB %d",
to);
if (err == -EIO)
ubi_warn("error %d while reading data back "
"from PEB %d", err, to);
if (is_error_sane(err))
err = MOVE_TARGET_RD_ERR;
} else
err = MOVE_CANCEL_BITFLIPS;