diff options
Diffstat (limited to 'fs/buffer.c')
-rw-r--r-- | fs/buffer.c | 59 |
1 files changed, 42 insertions, 17 deletions
diff --git a/fs/buffer.c b/fs/buffer.c index a08bb8e61c6..b0675bfe820 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -2331,24 +2331,26 @@ EXPORT_SYMBOL(block_commit_write); * page lock we can determine safely if the page is beyond EOF. If it is not * beyond EOF, then the page is guaranteed safe against truncation until we * unlock the page. + * + * Direct callers of this function should call vfs_check_frozen() so that page + * fault does not busyloop until the fs is thawed. */ -int -block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, - get_block_t get_block) +int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, + get_block_t get_block) { struct page *page = vmf->page; struct inode *inode = vma->vm_file->f_path.dentry->d_inode; unsigned long end; loff_t size; - int ret = VM_FAULT_NOPAGE; /* make the VM retry the fault */ + int ret; lock_page(page); size = i_size_read(inode); if ((page->mapping != inode->i_mapping) || (page_offset(page) > size)) { - /* page got truncated out from underneath us */ - unlock_page(page); - goto out; + /* We overload EFAULT to mean page got truncated */ + ret = -EFAULT; + goto out_unlock; } /* page is wholly or partially inside EOF */ @@ -2361,18 +2363,41 @@ block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, if (!ret) ret = block_commit_write(page, 0, end); - if (unlikely(ret)) { - unlock_page(page); - if (ret == -ENOMEM) - ret = VM_FAULT_OOM; - else /* -ENOSPC, -EIO, etc */ - ret = VM_FAULT_SIGBUS; - } else - ret = VM_FAULT_LOCKED; - -out: + if (unlikely(ret < 0)) + goto out_unlock; + /* + * Freezing in progress? We check after the page is marked dirty and + * with page lock held so if the test here fails, we are sure freezing + * code will wait during syncing until the page fault is done - at that + * point page will be dirty and unlocked so freezing code will write it + * and writeprotect it again. + */ + set_page_dirty(page); + if (inode->i_sb->s_frozen != SB_UNFROZEN) { + ret = -EAGAIN; + goto out_unlock; + } + return 0; +out_unlock: + unlock_page(page); return ret; } +EXPORT_SYMBOL(__block_page_mkwrite); + +int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, + get_block_t get_block) +{ + int ret; + struct super_block *sb = vma->vm_file->f_path.dentry->d_inode->i_sb; + + /* + * This check is racy but catches the common case. The check in + * __block_page_mkwrite() is reliable. + */ + vfs_check_frozen(sb, SB_FREEZE_WRITE); + ret = __block_page_mkwrite(vma, vmf, get_block); + return block_page_mkwrite_return(ret); +} EXPORT_SYMBOL(block_page_mkwrite); /* |