From: Miklos Szeredi <[EMAIL PROTECTED]>
Add a new semaphore to prevent asynchronous page writeback during the
TRUNCATE request.
Using i_alloc_sem would almost work, but it has to be released before
invalidating the truncated pages, so it's easier to define a separate
one.
Signed-off-by: Miklos Szeredi <[EMAIL PROTECTED]>
---
Index: linux/fs/fuse/dir.c
===================================================================
--- linux.orig/fs/fuse/dir.c 2007-02-27 14:41:10.000000000 +0100
+++ linux/fs/fuse/dir.c 2007-02-27 14:41:10.000000000 +0100
@@ -981,19 +981,9 @@ static void iattr_to_fattr(struct iattr
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);
- }
+ struct address_space *mapping = inode->i_mapping;
+ unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
+ truncate_inode_pages(mapping, offset);
}
/*
@@ -1037,6 +1027,9 @@ static int fuse_setattr(struct dentry *e
if (IS_ERR(req))
return PTR_ERR(req);
+ if (is_truncate)
+ down_write(&fi->truncate_sem);
+
memset(&inarg, 0, sizeof(inarg));
iattr_to_fattr(attr, &inarg);
req->in.h.opcode = FUSE_SETATTR;
@@ -1050,20 +1043,41 @@ static int fuse_setattr(struct dentry *e
request_send(fc, req);
err = req->out.h.error;
fuse_put_request(fc, req);
- if (!err) {
- if ((inode->i_mode ^ outarg.attr.mode) & S_IFMT) {
- make_bad_inode(inode);
- err = -EIO;
- } else {
- 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);
- }
- } else if (err == -EINTR)
+ if (err == -EINTR)
fuse_invalidate_attr(inode);
+ if (err)
+ goto out_err;
+ err = -EIO;
+ if ((inode->i_mode ^ outarg.attr.mode) & S_IFMT) {
+ make_bad_inode(inode);
+ goto out_err;
+ }
+
+ if (is_truncate) {
+ int need_trunc;
+
+ spin_lock(&fc->lock);
+ need_trunc = inode->i_size > outarg.attr.size;
+ i_size_write(inode, outarg.attr.size);
+ spin_unlock(&fc->lock);
+
+ /*
+ * Lock ordering is: page-lock -> truncate_sem, because
+ * writepage is called with a locked page. So release
+ * truncate_sem before truncating the mapping
+ */
+ up_write(&fi->truncate_sem);
+ if (need_trunc)
+ 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);
+ return 0;
+
+ out_err:
+ if (is_truncate)
+ up_write(&fi->truncate_sem);
return err;
}
Index: linux/fs/fuse/fuse_i.h
===================================================================
--- linux.orig/fs/fuse/fuse_i.h 2007-02-27 14:41:10.000000000 +0100
+++ linux/fs/fuse/fuse_i.h 2007-02-27 14:41:10.000000000 +0100
@@ -15,6 +15,7 @@
#include <linux/mm.h>
#include <linux/backing-dev.h>
#include <linux/mutex.h>
+#include <linux/rwsem.h>
/** Max number of pages that can be used in a single read request */
#define FUSE_MAX_PAGES_PER_REQ 32
@@ -63,6 +64,9 @@ struct fuse_inode {
/** Time in jiffies until the file attributes are valid */
u64 i_time;
+
+ /** Semaphore for synchronizing writes with truncate */
+ struct rw_semaphore truncate_sem;
};
/** FUSE specific file data */
Index: linux/fs/fuse/inode.c
===================================================================
--- linux.orig/fs/fuse/inode.c 2007-02-27 14:41:10.000000000 +0100
+++ linux/fs/fuse/inode.c 2007-02-27 14:41:10.000000000 +0100
@@ -55,6 +55,7 @@ static struct inode *fuse_alloc_inode(st
fi->i_time = 0;
fi->nodeid = 0;
fi->nlookup = 0;
+ init_rwsem(&fi->truncate_sem);
fi->forget_req = fuse_request_alloc();
if (!fi->forget_req) {
kmem_cache_free(fuse_inode_cachep, inode);
--
-
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