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Btrfs: fix several potential problems in copy_nocow_pages_for_inode

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- It makes no sense that we deal with a inode in the dead tree.
- fix the race between dio and page copy by waiting the dio completion
- avoid the page copy vs truncate/punch hole
- check if the page is in the page cache or not

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
This commit is contained in:
Miao Xie 2013-06-27 18:51:00 +08:00 committed by Josef Bacik
parent 826aa0a82c
commit edd1400be9
1 changed files with 22 additions and 1 deletions
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23
fs/btrfs/scrub.c
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@ -3224,6 +3224,11 @@ static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root, void *ctx)
return PTR_ERR(local_root);
}
if (btrfs_root_refs(&local_root->root_item) == 0) {
srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
return -ENOENT;
}
key.type = BTRFS_INODE_ITEM_KEY;
key.objectid = inum;
key.offset = 0;
@ -3232,12 +3237,16 @@ static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root, void *ctx)
if (IS_ERR(inode))
return PTR_ERR(inode);
/* Avoid truncate/dio/punch hole.. */
mutex_lock(&inode->i_mutex);
inode_dio_wait(inode);
ret = 0;
physical_for_dev_replace = nocow_ctx->physical_for_dev_replace;
len = nocow_ctx->len;
while (len >= PAGE_CACHE_SIZE) {
index = offset >> PAGE_CACHE_SHIFT;
again:
page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
if (!page) {
pr_err("find_or_create_page() failed\n");
@ -3258,7 +3267,18 @@ static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root, void *ctx)
ret = err;
goto next_page;
}
lock_page(page);
/*
* If the page has been remove from the page cache,
* the data on it is meaningless, because it may be
* old one, the new data may be written into the new
* page in the page cache.
*/
if (page->mapping != inode->i_mapping) {
page_cache_release(page);
goto again;
}
if (!PageUptodate(page)) {
ret = -EIO;
goto next_page;
@ -3280,6 +3300,7 @@ static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root, void *ctx)
len -= PAGE_CACHE_SIZE;
}
out:
mutex_unlock(&inode->i_mutex);
iput(inode);
return ret;
}