On Mon, 20 Jun 2011, Christoph Hellwig wrote: > Add a new rw_semaphore to protect page_mkwrite against truncate. Previous > i_alloc_sem was abused for this, but it's going away in this series. > > Signed-off-by: Christoph Hellwig <hch@xxxxxx> > > Index: linux-2.6/fs/ext4/inode.c > =================================================================== > --- linux-2.6.orig/fs/ext4/inode.c 2011-06-20 14:25:33.779248128 +0200 > +++ linux-2.6/fs/ext4/inode.c 2011-06-20 14:27:53.025907745 +0200 > @@ -5357,6 +5357,7 @@ int ext4_setattr(struct dentry *dentry, > if (attr->ia_size > sbi->s_bitmap_maxbytes) > return -EFBIG; > } > + down_write(&(EXT4_I(inode)->truncate_lock)); > } > > if (S_ISREG(inode->i_mode) && > @@ -5405,6 +5406,9 @@ int ext4_setattr(struct dentry *dentry, > ext4_truncate(inode); > } > > + if (attr->ia_valid & ATTR_SIZE) > + up_write(&(EXT4_I(inode)->truncate_lock)); > + Hi Christoph, this looks like a bug fix, so we should rather do it in a separate commit. Could you send it separately, or at least mention that in commit description ? Otherwise the patch looks good. Thanks! -Lukas > if (!rc) { > setattr_copy(inode, attr); > mark_inode_dirty(inode); > @@ -5850,10 +5854,10 @@ int ext4_page_mkwrite(struct vm_area_str > struct address_space *mapping = inode->i_mapping; > > /* > - * Get i_alloc_sem to stop truncates messing with the inode. We cannot > - * get i_mutex because we are already holding mmap_sem. > + * Get truncate_lock to stop truncates messing with the inode. We > + * cannot get i_mutex because we are already holding mmap_sem. > */ > - down_read(&inode->i_alloc_sem); > + down_read(&(EXT4_I(inode)->truncate_lock)); > size = i_size_read(inode); > if (page->mapping != mapping || size <= page_offset(page) > || !PageUptodate(page)) { > @@ -5865,7 +5869,7 @@ int ext4_page_mkwrite(struct vm_area_str > lock_page(page); > wait_on_page_writeback(page); > if (PageMappedToDisk(page)) { > - up_read(&inode->i_alloc_sem); > + up_read(&(EXT4_I(inode)->truncate_lock)); > return VM_FAULT_LOCKED; > } > > @@ -5883,7 +5887,7 @@ int ext4_page_mkwrite(struct vm_area_str > if (page_has_buffers(page)) { > if (!walk_page_buffers(NULL, page_buffers(page), 0, len, NULL, > ext4_bh_unmapped)) { > - up_read(&inode->i_alloc_sem); > + up_read(&(EXT4_I(inode)->truncate_lock)); > return VM_FAULT_LOCKED; > } > } > @@ -5912,11 +5916,11 @@ int ext4_page_mkwrite(struct vm_area_str > */ > lock_page(page); > wait_on_page_writeback(page); > - up_read(&inode->i_alloc_sem); > + up_read(&(EXT4_I(inode)->truncate_lock)); > return VM_FAULT_LOCKED; > out_unlock: > if (ret) > ret = VM_FAULT_SIGBUS; > - up_read(&inode->i_alloc_sem); > + up_read(&(EXT4_I(inode)->truncate_lock)); > return ret; > } > Index: linux-2.6/fs/ext4/super.c > =================================================================== > --- linux-2.6.orig/fs/ext4/super.c 2011-06-20 14:25:33.795914793 +0200 > +++ linux-2.6/fs/ext4/super.c 2011-06-20 14:27:06.269243443 +0200 > @@ -871,6 +871,7 @@ static struct inode *ext4_alloc_inode(st > ei->i_datasync_tid = 0; > atomic_set(&ei->i_ioend_count, 0); > atomic_set(&ei->i_aiodio_unwritten, 0); > + init_rwsem(&ei->truncate_lock); > > return &ei->vfs_inode; > } > Index: linux-2.6/fs/ext4/ext4.h > =================================================================== > --- linux-2.6.orig/fs/ext4/ext4.h 2011-06-20 14:25:33.752581461 +0200 > +++ linux-2.6/fs/ext4/ext4.h 2011-06-20 14:27:06.272576777 +0200 > @@ -844,6 +844,9 @@ struct ext4_inode_info { > /* on-disk additional length */ > __u16 i_extra_isize; > > + /* protect page_mkwrite against truncates */ > + struct rw_semaphore truncate_lock; > + > #ifdef CONFIG_QUOTA > /* quota space reservation, managed internally by quota code */ > qsize_t i_reserved_quota; > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html