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ufs_get_locked_page(): make sure we have buffer_heads

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callers rely upon that, but find_lock_page() racing with attempt of
page eviction by memory pressure might have left us with
	* try_to_free_buffers() successfully done
	* __remove_mapping() failed, leaving the page in our mapping
	* find_lock_page() returning an uptodate page with no
buffer_heads attached.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2017-06-14 23:32:19 -04:00
parent c596961d1b
commit 267309f394
1 changed files with 8 additions and 9 deletions
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17
fs/ufs/util.c
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@ -243,9 +243,8 @@ ufs_set_inode_dev(struct super_block *sb, struct ufs_inode_info *ufsi, dev_t dev
struct page *ufs_get_locked_page(struct address_space *mapping,
pgoff_t index)
{
struct page *page;
page = find_lock_page(mapping, index);
struct inode *inode = mapping->host;
struct page *page = find_lock_page(mapping, index);
if (!page) {
page = read_mapping_page(mapping, index, NULL);
@ -253,7 +252,7 @@ struct page *ufs_get_locked_page(struct address_space *mapping,
printk(KERN_ERR "ufs_change_blocknr: "
"read_mapping_page error: ino %lu, index: %lu\n",
mapping->host->i_ino, index);
goto out;
return page;
}
lock_page(page);
@ -262,8 +261,7 @@ struct page *ufs_get_locked_page(struct address_space *mapping,
/* Truncate got there first */
unlock_page(page);
put_page(page);
page = NULL;
goto out;
return NULL;
}
if (!PageUptodate(page) || PageError(page)) {
@ -272,11 +270,12 @@ struct page *ufs_get_locked_page(struct address_space *mapping,
printk(KERN_ERR "ufs_change_blocknr: "
"can not read page: ino %lu, index: %lu\n",
mapping->host->i_ino, index);
inode->i_ino, index);
page = ERR_PTR(-EIO);
return ERR_PTR(-EIO);
}
}
out:
if (!page_has_buffers(page))
create_empty_buffers(page, 1 << inode->i_blkbits, 0);
return page;
}