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Commit 58268691 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Al Viro
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fat: remove i_alloc_sem abuse 



Add a new rw_semaphore to protect bmap against truncate.  Previous
i_alloc_sem was abused for this, but it's going away in this series.

Note that we can't simply use i_mutex, given that the swapon code
calls ->bmap under it.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 8c5dc70a

fs/fat/fat.h

+1 −0
Original line number Diff line number Diff line
@@ -109,6 +109,7 @@ struct msdos_inode_info { 
	int i_attrs;		/* unused attribute bits */

	loff_t i_pos;		/* on-disk position of directory entry or 0 */

	struct hlist_node i_fat_hash;	/* hash by i_location */

	struct rw_semaphore truncate_lock; /* protect bmap against truncate */

	struct inode vfs_inode;

};

fs/fat/file.c

+2 −0
Original line number Diff line number Diff line
@@ -429,8 +429,10 @@ int fat_setattr(struct dentry *dentry, struct iattr *attr) 
	}



	if (attr->ia_valid & ATTR_SIZE) {

		down_write(&MSDOS_I(inode)->truncate_lock);

		truncate_setsize(inode, attr->ia_size);

		fat_truncate_blocks(inode, attr->ia_size);

		up_write(&MSDOS_I(inode)->truncate_lock);

	}



	setattr_copy(inode, attr);

fs/fat/inode.c

+4 −2
Original line number Diff line number Diff line
@@ -224,9 +224,9 @@ static sector_t _fat_bmap(struct address_space *mapping, sector_t block) 
	sector_t blocknr;



	/* fat_get_cluster() assumes the requested blocknr isn't truncated. */

	down_read(&mapping->host->i_alloc_sem);

	down_read(&MSDOS_I(mapping->host)->truncate_lock);

	blocknr = generic_block_bmap(mapping, block, fat_get_block);

	up_read(&mapping->host->i_alloc_sem);

	up_read(&MSDOS_I(mapping->host)->truncate_lock);



	return blocknr;

}
@@ -510,6 +510,8 @@ static struct inode *fat_alloc_inode(struct super_block *sb) 
	ei = kmem_cache_alloc(fat_inode_cachep, GFP_NOFS);

	if (!ei)

		return NULL;



	init_rwsem(&ei->truncate_lock);

	return &ei->vfs_inode;

}