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>
diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index 8276cc2..a975b41 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -109,6 +109,7 @@
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;
};
diff --git a/fs/fat/file.c b/fs/fat/file.c
index 7018e1d..a4a3a3c 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -429,8 +429,10 @@
}
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);
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index cb8d839..3decce4 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -224,9 +224,9 @@
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 @@
ei = kmem_cache_alloc(fat_inode_cachep, GFP_NOFS);
if (!ei)
return NULL;
+
+ init_rwsem(&ei->truncate_lock);
return &ei->vfs_inode;
}