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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: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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@ -109,6 +109,7 @@ struct msdos_inode_info {
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int i_attrs; /* unused attribute bits */
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loff_t i_pos; /* on-disk position of directory entry or 0 */
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struct hlist_node i_fat_hash; /* hash by i_location */
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struct rw_semaphore truncate_lock; /* protect bmap against truncate */
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struct inode vfs_inode;
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};
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@ -429,8 +429,10 @@ int fat_setattr(struct dentry *dentry, struct iattr *attr)
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}
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if (attr->ia_valid & ATTR_SIZE) {
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down_write(&MSDOS_I(inode)->truncate_lock);
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truncate_setsize(inode, attr->ia_size);
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fat_truncate_blocks(inode, attr->ia_size);
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up_write(&MSDOS_I(inode)->truncate_lock);
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}
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setattr_copy(inode, attr);
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@ -224,9 +224,9 @@ static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
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sector_t blocknr;
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/* fat_get_cluster() assumes the requested blocknr isn't truncated. */
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down_read(&mapping->host->i_alloc_sem);
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down_read(&MSDOS_I(mapping->host)->truncate_lock);
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blocknr = generic_block_bmap(mapping, block, fat_get_block);
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up_read(&mapping->host->i_alloc_sem);
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up_read(&MSDOS_I(mapping->host)->truncate_lock);
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return blocknr;
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}
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@ -510,6 +510,8 @@ static struct inode *fat_alloc_inode(struct super_block *sb)
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ei = kmem_cache_alloc(fat_inode_cachep, GFP_NOFS);
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if (!ei)
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return NULL;
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init_rwsem(&ei->truncate_lock);
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return &ei->vfs_inode;
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}
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