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    DateFri, 10 Mar 2006 11:08:29 +0300
    FromKirill Korotaev <>
    Subject[PATCH] ext3: ext3_symlink should use GFP_NOFS allocations inside
    Andrew,
    
    Resending a patch with a separate helper as requested by Al Viro:
    
    This patch fixes illegal __GFP_FS allocation inside ext3
    transaction in ext3_symlink().
    Such allocation may re-enter ext3 code from
    try_to_free_pages. But JBD/ext3 code keeps a pointer to current
    journal handle in task_struct and, hence, is not reentrable.
    
    This bug led to "Assertion failure in journal_dirty_metadata()" messages.
    
    http://bugzilla.openvz.org/show_bug.cgi?id=115
    
    Signed-Off-By: Andrey Savochkin <saw@saw.sw.com.sg>
    Signed-Off-By: Kirill Korotaev <dev@openvz.org>
    
    Thanks,
    Kirill
    P.S. against 2.6.16-rc5
    --- ./fs/ext3/namei.c.symlnkfix	2006-03-10 10:24:05.000000000 +0300
    +++ ./fs/ext3/namei.c	2006-03-10 10:24:49.000000000 +0300
    @@ -2141,7 +2141,7 @@ retry:
     		 * We have a transaction open.  All is sweetness.  It also sets
     		 * i_size in generic_commit_write().
     		 */
    -		err = page_symlink(inode, symname, l);
    +		err = __page_symlink(inode, symname, l, GFP_NOFS);
     		if (err) {
     			ext3_dec_count(handle, inode);
     			ext3_mark_inode_dirty(handle, inode);
    --- ./fs/namei.c.symlnkfix	2006-03-10 10:24:05.000000000 +0300
    +++ ./fs/namei.c	2006-03-10 10:34:58.000000000 +0300
    @@ -2613,13 +2613,16 @@ void page_put_link(struct dentry *dentry
     	}
     }
     
    -int page_symlink(struct inode *inode, const char *symname, int len)
    +int __page_symlink(struct inode *inode, const char *symname, int len,
    +		gfp_t gfp_mask)
     {
     	struct address_space *mapping = inode->i_mapping;
    -	struct page *page = grab_cache_page(mapping, 0);
    +	struct page *page;
     	int err = -ENOMEM;
     	char *kaddr;
     
    +	page = find_or_create_page(mapping, 0,
    +			mapping_gfp_mask(mapping) | gfp_mask);
     	if (!page)
     		goto fail;
     	err = mapping->a_ops->prepare_write(NULL, page, 0, len-1);
    @@ -2654,6 +2657,11 @@ fail:
     	return err;
     }
     
    +int page_symlink(struct inode *inode, const char *symname, int len)
    +{
    +	return __page_symlink(inode, symname, len, GFP_KERNEL);
    +}
    +
     struct inode_operations page_symlink_inode_operations = {
     	.readlink	= generic_readlink,
     	.follow_link	= page_follow_link_light,
    @@ -2672,6 +2680,7 @@ EXPORT_SYMBOL(lookup_one_len);
     EXPORT_SYMBOL(page_follow_link_light);
     EXPORT_SYMBOL(page_put_link);
     EXPORT_SYMBOL(page_readlink);
    +EXPORT_SYMBOL(__page_symlink);
     EXPORT_SYMBOL(page_symlink);
     EXPORT_SYMBOL(page_symlink_inode_operations);
     EXPORT_SYMBOL(path_lookup);
    --- ./include/linux/fs.h.symlnkfix	2006-03-10 10:24:05.000000000 +0300
    +++ ./include/linux/fs.h	2006-03-10 10:27:40.000000000 +0300
    @@ -1669,6 +1669,8 @@ extern int vfs_follow_link(struct nameid
     extern int page_readlink(struct dentry *, char __user *, int);
     extern void *page_follow_link_light(struct dentry *, struct nameidata *);
     extern void page_put_link(struct dentry *, struct nameidata *, void *);
    +extern int __page_symlink(struct inode *inode, const char *symname, int len,
    +		gfp_t gfp_mask);
     extern int page_symlink(struct inode *inode, const char *symname, int len);
     extern struct inode_operations page_symlink_inode_operations;
     extern int generic_readlink(struct dentry *, char __user *, int);
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