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Btrfs: split bio_readpage_error into several functions
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The data repair function of direct read will be implemented later, and some code
in bio_readpage_error will be reused, so split bio_readpage_error into
several functions which will be used in direct read repair later.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
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Miao Xie authored and Chris Mason committed Sep 17, 2014
1 parent 454ff3d commit 2fe6303
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Showing 2 changed files with 123 additions and 64 deletions.
159 changes: 95 additions & 64 deletions fs/btrfs/extent_io.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1962,25 +1962,6 @@ static void check_page_uptodate(struct extent_io_tree *tree, struct page *page)
SetPageUptodate(page);
}

/*
* When IO fails, either with EIO or csum verification fails, we
* try other mirrors that might have a good copy of the data. This
* io_failure_record is used to record state as we go through all the
* mirrors. If another mirror has good data, the page is set up to date
* and things continue. If a good mirror can't be found, the original
* bio end_io callback is called to indicate things have failed.
*/
struct io_failure_record {
struct page *page;
u64 start;
u64 len;
u64 logical;
unsigned long bio_flags;
int this_mirror;
int failed_mirror;
int in_validation;
};

static int free_io_failure(struct inode *inode, struct io_failure_record *rec)
{
int ret;
Expand Down Expand Up @@ -2156,40 +2137,24 @@ static int clean_io_failure(u64 start, struct page *page)
return 0;
}

/*
* this is a generic handler for readpage errors (default
* readpage_io_failed_hook). if other copies exist, read those and write back
* good data to the failed position. does not investigate in remapping the
* failed extent elsewhere, hoping the device will be smart enough to do this as
* needed
*/

static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
struct page *page, u64 start, u64 end,
int failed_mirror)
int btrfs_get_io_failure_record(struct inode *inode, u64 start, u64 end,
struct io_failure_record **failrec_ret)
{
struct io_failure_record *failrec = NULL;
struct io_failure_record *failrec;
u64 private;
struct extent_map *em;
struct inode *inode = page->mapping->host;
struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
struct bio *bio;
struct btrfs_io_bio *btrfs_failed_bio;
struct btrfs_io_bio *btrfs_bio;
int num_copies;
int ret;
int read_mode;
u64 logical;

BUG_ON(failed_bio->bi_rw & REQ_WRITE);

ret = get_state_private(failure_tree, start, &private);
if (ret) {
failrec = kzalloc(sizeof(*failrec), GFP_NOFS);
if (!failrec)
return -ENOMEM;

failrec->start = start;
failrec->len = end - start + 1;
failrec->this_mirror = 0;
Expand All @@ -2209,11 +2174,11 @@ static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
em = NULL;
}
read_unlock(&em_tree->lock);

if (!em) {
kfree(failrec);
return -EIO;
}

logical = start - em->start;
logical = em->block_start + logical;
if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
Expand All @@ -2222,8 +2187,10 @@ static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
extent_set_compress_type(&failrec->bio_flags,
em->compress_type);
}
pr_debug("bio_readpage_error: (new) logical=%llu, start=%llu, "
"len=%llu\n", logical, start, failrec->len);

pr_debug("Get IO Failure Record: (new) logical=%llu, start=%llu, len=%llu\n",
logical, start, failrec->len);

failrec->logical = logical;
free_extent_map(em);

Expand All @@ -2243,8 +2210,7 @@ static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
}
} else {
failrec = (struct io_failure_record *)(unsigned long)private;
pr_debug("bio_readpage_error: (found) logical=%llu, "
"start=%llu, len=%llu, validation=%d\n",
pr_debug("Get IO Failure Record: (found) logical=%llu, start=%llu, len=%llu, validation=%d\n",
failrec->logical, failrec->start, failrec->len,
failrec->in_validation);
/*
Expand All @@ -2253,6 +2219,17 @@ static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
* clean_io_failure() clean all those errors at once.
*/
}

*failrec_ret = failrec;

return 0;
}

int btrfs_check_repairable(struct inode *inode, struct bio *failed_bio,
struct io_failure_record *failrec, int failed_mirror)
{
int num_copies;

num_copies = btrfs_num_copies(BTRFS_I(inode)->root->fs_info,
failrec->logical, failrec->len);
if (num_copies == 1) {
Expand All @@ -2261,10 +2238,9 @@ static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
* all the retry and error correction code that follows. no
* matter what the error is, it is very likely to persist.
*/
pr_debug("bio_readpage_error: cannot repair, num_copies=%d, next_mirror %d, failed_mirror %d\n",
pr_debug("Check Repairable: cannot repair, num_copies=%d, next_mirror %d, failed_mirror %d\n",
num_copies, failrec->this_mirror, failed_mirror);
free_io_failure(inode, failrec);
return -EIO;
return 0;
}

/*
Expand All @@ -2284,7 +2260,6 @@ static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
BUG_ON(failrec->in_validation);
failrec->in_validation = 1;
failrec->this_mirror = failed_mirror;
read_mode = READ_SYNC | REQ_FAILFAST_DEV;
} else {
/*
* we're ready to fulfill a) and b) alongside. get a good copy
Expand All @@ -2300,22 +2275,32 @@ static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
failrec->this_mirror++;
if (failrec->this_mirror == failed_mirror)
failrec->this_mirror++;
read_mode = READ_SYNC;
}

if (failrec->this_mirror > num_copies) {
pr_debug("bio_readpage_error: (fail) num_copies=%d, next_mirror %d, failed_mirror %d\n",
pr_debug("Check Repairable: (fail) num_copies=%d, next_mirror %d, failed_mirror %d\n",
num_copies, failrec->this_mirror, failed_mirror);
free_io_failure(inode, failrec);
return -EIO;
return 0;
}

return 1;
}


struct bio *btrfs_create_repair_bio(struct inode *inode, struct bio *failed_bio,
struct io_failure_record *failrec,
struct page *page, int pg_offset, int icsum,
bio_end_io_t *endio_func)
{
struct bio *bio;
struct btrfs_io_bio *btrfs_failed_bio;
struct btrfs_io_bio *btrfs_bio;

bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
if (!bio) {
free_io_failure(inode, failrec);
return -EIO;
}
bio->bi_end_io = failed_bio->bi_end_io;
if (!bio)
return NULL;

bio->bi_end_io = endio_func;
bio->bi_iter.bi_sector = failrec->logical >> 9;
bio->bi_bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
bio->bi_iter.bi_size = 0;
Expand All @@ -2327,17 +2312,63 @@ static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,

btrfs_bio = btrfs_io_bio(bio);
btrfs_bio->csum = btrfs_bio->csum_inline;
phy_offset >>= inode->i_sb->s_blocksize_bits;
phy_offset *= csum_size;
memcpy(btrfs_bio->csum, btrfs_failed_bio->csum + phy_offset,
icsum *= csum_size;
memcpy(btrfs_bio->csum, btrfs_failed_bio->csum + icsum,
csum_size);
}

bio_add_page(bio, page, failrec->len, start - page_offset(page));
bio_add_page(bio, page, failrec->len, pg_offset);

return bio;
}

/*
* this is a generic handler for readpage errors (default
* readpage_io_failed_hook). if other copies exist, read those and write back
* good data to the failed position. does not investigate in remapping the
* failed extent elsewhere, hoping the device will be smart enough to do this as
* needed
*/

static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
struct page *page, u64 start, u64 end,
int failed_mirror)
{
struct io_failure_record *failrec;
struct inode *inode = page->mapping->host;
struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
struct bio *bio;
int read_mode;
int ret;

BUG_ON(failed_bio->bi_rw & REQ_WRITE);

ret = btrfs_get_io_failure_record(inode, start, end, &failrec);
if (ret)
return ret;

ret = btrfs_check_repairable(inode, failed_bio, failrec, failed_mirror);
if (!ret) {
free_io_failure(inode, failrec);
return -EIO;
}

if (failed_bio->bi_vcnt > 1)
read_mode = READ_SYNC | REQ_FAILFAST_DEV;
else
read_mode = READ_SYNC;

phy_offset >>= inode->i_sb->s_blocksize_bits;
bio = btrfs_create_repair_bio(inode, failed_bio, failrec, page,
start - page_offset(page),
(int)phy_offset, failed_bio->bi_end_io);
if (!bio) {
free_io_failure(inode, failrec);
return -EIO;
}

pr_debug("bio_readpage_error: submitting new read[%#x] to "
"this_mirror=%d, num_copies=%d, in_validation=%d\n", read_mode,
failrec->this_mirror, num_copies, failrec->in_validation);
pr_debug("Repair Read Error: submitting new read[%#x] to this_mirror=%d, in_validation=%d\n",
read_mode, failrec->this_mirror, failrec->in_validation);

ret = tree->ops->submit_bio_hook(inode, read_mode, bio,
failrec->this_mirror,
Expand Down
28 changes: 28 additions & 0 deletions fs/btrfs/extent_io.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -344,6 +344,34 @@ int repair_io_failure(struct btrfs_fs_info *fs_info, u64 start,
int end_extent_writepage(struct page *page, int err, u64 start, u64 end);
int repair_eb_io_failure(struct btrfs_root *root, struct extent_buffer *eb,
int mirror_num);

/*
* When IO fails, either with EIO or csum verification fails, we
* try other mirrors that might have a good copy of the data. This
* io_failure_record is used to record state as we go through all the
* mirrors. If another mirror has good data, the page is set up to date
* and things continue. If a good mirror can't be found, the original
* bio end_io callback is called to indicate things have failed.
*/
struct io_failure_record {
struct page *page;
u64 start;
u64 len;
u64 logical;
unsigned long bio_flags;
int this_mirror;
int failed_mirror;
int in_validation;
};

int btrfs_get_io_failure_record(struct inode *inode, u64 start, u64 end,
struct io_failure_record **failrec_ret);
int btrfs_check_repairable(struct inode *inode, struct bio *failed_bio,
struct io_failure_record *failrec, int fail_mirror);
struct bio *btrfs_create_repair_bio(struct inode *inode, struct bio *failed_bio,
struct io_failure_record *failrec,
struct page *page, int pg_offset, int icsum,
bio_end_io_t *endio_func);
#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
noinline u64 find_lock_delalloc_range(struct inode *inode,
struct extent_io_tree *tree,
Expand Down

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