[PATCH] fuse: fix hang on SMP
Fuse didn't always call i_size_write() with i_mutex held which caused rare
hangs on SMP/32bit. This bug has been present since fuse-2.2, well before
being merged into mainline.
The simplest solution is to protect i_size_write() with the per-connection
spinlock. Using i_mutex for this purpose would require some restructuring of
the code and I'm not even sure it's always safe to acquire i_mutex in all
places i_size needs to be set.
Since most of vmtruncate is already duplicated for other reasons, duplicate
the remaining part as well, making all i_size_write() calls internal to fuse.
Using i_size_write() was unnecessary in fuse_init_inode(), since this function
is only called on a newly created locked inode.
Reported by a few people over the years, but special thanks to Dana Henriksen
who was persistent enough in helping me debug it.
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 8605155..a8f65c1 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -935,14 +935,30 @@
}
}
+static void fuse_vmtruncate(struct inode *inode, loff_t offset)
+{
+ struct fuse_conn *fc = get_fuse_conn(inode);
+ int need_trunc;
+
+ spin_lock(&fc->lock);
+ need_trunc = inode->i_size > offset;
+ i_size_write(inode, offset);
+ spin_unlock(&fc->lock);
+
+ if (need_trunc) {
+ struct address_space *mapping = inode->i_mapping;
+ unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
+ truncate_inode_pages(mapping, offset);
+ }
+}
+
/*
* Set attributes, and at the same time refresh them.
*
* Truncation is slightly complicated, because the 'truncate' request
* may fail, in which case we don't want to touch the mapping.
- * vmtruncate() doesn't allow for this case. So do the rlimit
- * checking by hand and call vmtruncate() only after the file has
- * actually been truncated.
+ * vmtruncate() doesn't allow for this case, so do the rlimit checking
+ * and the actual truncation by hand.
*/
static int fuse_setattr(struct dentry *entry, struct iattr *attr)
{
@@ -993,12 +1009,8 @@
make_bad_inode(inode);
err = -EIO;
} else {
- if (is_truncate) {
- loff_t origsize = i_size_read(inode);
- i_size_write(inode, outarg.attr.size);
- if (origsize > outarg.attr.size)
- vmtruncate(inode, outarg.attr.size);
- }
+ if (is_truncate)
+ fuse_vmtruncate(inode, outarg.attr.size);
fuse_change_attributes(inode, &outarg.attr);
fi->i_time = time_to_jiffies(outarg.attr_valid,
outarg.attr_valid_nsec);