From 8e52acf70459020d7e9e9fda25066be4da520943 Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Mon, 12 Mar 2012 16:39:28 +0800 Subject: Btrfs: retrurn void from clear_state_bit Currently it returns a set of bits that were cleared, but this return value is not used at all. Moreover it doesn't seem to be useful, because we may clear the bits of a few extent_states, but only the cleared bits of last one is returned. Signed-off-by: Li Zefan --- fs/btrfs/extent_io.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) (limited to 'fs/btrfs/extent_io.c') diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 4789770f8ea..05951bdf72c 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -404,18 +404,16 @@ static int split_state(struct extent_io_tree *tree, struct extent_state *orig, /* * utility function to clear some bits in an extent state struct. - * it will optionally wake up any one waiting on this state (wake == 1), or - * forcibly remove the state from the tree (delete == 1). + * it will optionally wake up any one waiting on this state (wake == 1) * * If no bits are set on the state struct after clearing things, the * struct is freed and removed from the tree */ -static int clear_state_bit(struct extent_io_tree *tree, +static void clear_state_bit(struct extent_io_tree *tree, struct extent_state *state, int *bits, int wake) { int bits_to_clear = *bits & ~EXTENT_CTLBITS; - int ret = state->state & bits_to_clear; if ((bits_to_clear & EXTENT_DIRTY) && (state->state & EXTENT_DIRTY)) { u64 range = state->end - state->start + 1; @@ -437,7 +435,6 @@ static int clear_state_bit(struct extent_io_tree *tree, } else { merge_state(tree, state); } - return ret; } static struct extent_state * -- cgit v1.2.3-70-g09d2 From cdc6a3952558f00b1bc3b6401e1cf98797632fe2 Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Mon, 12 Mar 2012 16:39:48 +0800 Subject: Btrfs: avoid possible use-after-free in clear_extent_bit() clear_extent_bit() { next_node = rb_next(&state->rb_node); ... clear_state_bit(state); <-- this may free next_node if (next_node) { state = rb_entry(next_node); ... } } clear_state_bit() calls merge_state() which may free the next node of the passing extent_state, so clear_extent_bit() may end up referencing freed memory. Signed-off-by: Li Zefan --- fs/btrfs/extent_io.c | 36 +++++++++++++++++++++--------------- 1 file changed, 21 insertions(+), 15 deletions(-) (limited to 'fs/btrfs/extent_io.c') diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 05951bdf72c..11eeb81fe69 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -402,6 +402,15 @@ static int split_state(struct extent_io_tree *tree, struct extent_state *orig, return 0; } +static struct extent_state *next_state(struct extent_state *state) +{ + struct rb_node *next = rb_next(&state->rb_node); + if (next) + return rb_entry(next, struct extent_state, rb_node); + else + return NULL; +} + /* * utility function to clear some bits in an extent state struct. * it will optionally wake up any one waiting on this state (wake == 1) @@ -409,10 +418,11 @@ static int split_state(struct extent_io_tree *tree, struct extent_state *orig, * If no bits are set on the state struct after clearing things, the * struct is freed and removed from the tree */ -static void clear_state_bit(struct extent_io_tree *tree, - struct extent_state *state, - int *bits, int wake) +static struct extent_state *clear_state_bit(struct extent_io_tree *tree, + struct extent_state *state, + int *bits, int wake) { + struct extent_state *next; int bits_to_clear = *bits & ~EXTENT_CTLBITS; if ((bits_to_clear & EXTENT_DIRTY) && (state->state & EXTENT_DIRTY)) { @@ -425,6 +435,7 @@ static void clear_state_bit(struct extent_io_tree *tree, if (wake) wake_up(&state->wq); if (state->state == 0) { + next = next_state(state); if (state->tree) { rb_erase(&state->rb_node, &tree->state); state->tree = NULL; @@ -434,7 +445,9 @@ static void clear_state_bit(struct extent_io_tree *tree, } } else { merge_state(tree, state); + next = next_state(state); } + return next; } static struct extent_state * @@ -473,7 +486,6 @@ int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, struct extent_state *state; struct extent_state *cached; struct extent_state *prealloc = NULL; - struct rb_node *next_node; struct rb_node *node; u64 last_end; int err; @@ -525,14 +537,11 @@ hit_next: WARN_ON(state->end < start); last_end = state->end; - if (state->end < end && !need_resched()) - next_node = rb_next(&state->rb_node); - else - next_node = NULL; - /* the state doesn't have the wanted bits, go ahead */ - if (!(state->state & bits)) + if (!(state->state & bits)) { + state = next_state(state); goto next; + } /* * | ---- desired range ---- | @@ -590,16 +599,13 @@ hit_next: goto out; } - clear_state_bit(tree, state, &bits, wake); + state = clear_state_bit(tree, state, &bits, wake); next: if (last_end == (u64)-1) goto out; start = last_end + 1; - if (start <= end && next_node) { - state = rb_entry(next_node, struct extent_state, - rb_node); + if (start <= end && state && !need_resched()) goto hit_next; - } goto search_again; out: -- cgit v1.2.3-70-g09d2 From 5cf1ab56133ad7b712673c071b439d4a555a2d1e Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Mon, 16 Apr 2012 09:42:26 -0400 Subject: Btrfs: always store the mirror we read the eb from A user reported a panic where we were trying to fix a bad mirror but the mirror number we were giving was 0, which is invalid. This is because we don't do the transid verification until after the read, so as far as the read code is concerned the read was a success. So instead store the mirror we read from so that if there is some failure post read we know which mirror to try next and which mirror needs to be fixed if we find a good copy of the block. Thanks, Signed-off-by: Josef Bacik --- fs/btrfs/disk-io.c | 16 ++++++++-------- fs/btrfs/extent_io.c | 15 ++++++--------- fs/btrfs/extent_io.h | 4 ++-- fs/btrfs/inode.c | 2 +- 4 files changed, 17 insertions(+), 20 deletions(-) (limited to 'fs/btrfs/extent_io.c') diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index b9866f27ebd..d0c969beaad 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -383,17 +383,16 @@ static int btree_read_extent_buffer_pages(struct btrfs_root *root, if (test_bit(EXTENT_BUFFER_CORRUPT, &eb->bflags)) break; - if (!failed_mirror) { - failed = 1; - printk(KERN_ERR "failed mirror was %d\n", eb->failed_mirror); - failed_mirror = eb->failed_mirror; - } - num_copies = btrfs_num_copies(&root->fs_info->mapping_tree, eb->start, eb->len); if (num_copies == 1) break; + if (!failed_mirror) { + failed = 1; + failed_mirror = eb->read_mirror; + } + mirror_num++; if (mirror_num == failed_mirror) mirror_num++; @@ -564,7 +563,7 @@ struct extent_buffer *find_eb_for_page(struct extent_io_tree *tree, } static int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end, - struct extent_state *state) + struct extent_state *state, int mirror) { struct extent_io_tree *tree; u64 found_start; @@ -589,6 +588,7 @@ static int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end, if (!reads_done) goto err; + eb->read_mirror = mirror; if (test_bit(EXTENT_BUFFER_IOERR, &eb->bflags)) { ret = -EIO; goto err; @@ -652,7 +652,7 @@ static int btree_io_failed_hook(struct page *page, int failed_mirror) eb = (struct extent_buffer *)page->private; set_bit(EXTENT_BUFFER_IOERR, &eb->bflags); - eb->failed_mirror = failed_mirror; + eb->read_mirror = failed_mirror; if (test_and_clear_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags)) btree_readahead_hook(root, eb, eb->start, -EIO); return -EIO; /* we fixed nothing */ diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 11eeb81fe69..0c23e57077c 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -2304,7 +2304,7 @@ static void end_bio_extent_readpage(struct bio *bio, int err) u64 start; u64 end; int whole_page; - int failed_mirror; + int mirror; int ret; if (err) @@ -2343,20 +2343,18 @@ static void end_bio_extent_readpage(struct bio *bio, int err) } spin_unlock(&tree->lock); + mirror = (int)(unsigned long)bio->bi_bdev; if (uptodate && tree->ops && tree->ops->readpage_end_io_hook) { ret = tree->ops->readpage_end_io_hook(page, start, end, - state); + state, mirror); if (ret) uptodate = 0; else clean_io_failure(start, page); } - if (!uptodate) - failed_mirror = (int)(unsigned long)bio->bi_bdev; - if (!uptodate && tree->ops && tree->ops->readpage_io_failed_hook) { - ret = tree->ops->readpage_io_failed_hook(page, failed_mirror); + ret = tree->ops->readpage_io_failed_hook(page, mirror); if (!ret && !err && test_bit(BIO_UPTODATE, &bio->bi_flags)) uptodate = 1; @@ -2371,8 +2369,7 @@ static void end_bio_extent_readpage(struct bio *bio, int err) * can't handle the error it will return -EIO and we * remain responsible for that page. */ - ret = bio_readpage_error(bio, page, start, end, - failed_mirror, NULL); + ret = bio_readpage_error(bio, page, start, end, mirror, NULL); if (ret == 0) { uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); @@ -4465,7 +4462,7 @@ int read_extent_buffer_pages(struct extent_io_tree *tree, } clear_bit(EXTENT_BUFFER_IOERR, &eb->bflags); - eb->failed_mirror = 0; + eb->read_mirror = 0; atomic_set(&eb->io_pages, num_reads); for (i = start_i; i < num_pages; i++) { page = extent_buffer_page(eb, i); diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h index faf10eb57f7..b516c3b8dec 100644 --- a/fs/btrfs/extent_io.h +++ b/fs/btrfs/extent_io.h @@ -79,7 +79,7 @@ struct extent_io_ops { u64 start, u64 end, struct extent_state *state); int (*readpage_end_io_hook)(struct page *page, u64 start, u64 end, - struct extent_state *state); + struct extent_state *state, int mirror); int (*writepage_end_io_hook)(struct page *page, u64 start, u64 end, struct extent_state *state, int uptodate); void (*set_bit_hook)(struct inode *inode, struct extent_state *state, @@ -135,7 +135,7 @@ struct extent_buffer { spinlock_t refs_lock; atomic_t refs; atomic_t io_pages; - int failed_mirror; + int read_mirror; struct list_head leak_list; struct rcu_head rcu_head; pid_t lock_owner; diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 98ee5a51aa2..d953f882046 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -1947,7 +1947,7 @@ static int btrfs_writepage_end_io_hook(struct page *page, u64 start, u64 end, * extent_io.c will try to find good copies for us. */ static int btrfs_readpage_end_io_hook(struct page *page, u64 start, u64 end, - struct extent_state *state) + struct extent_state *state, int mirror) { size_t offset = start - ((u64)page->index << PAGE_CACHE_SHIFT); struct inode *inode = page->mapping->host; -- cgit v1.2.3-70-g09d2