| Message ID | 1326331253-6497-3-git-send-email-jack@suse.cz |
|---|---|
| State | New, archived |
| Headers | show |
On 2012-01-11, at 6:20 PM, Jan Kara wrote: > There are three entry points which dirty pages in a filesystem. mmap (handled > by block_page_mkwrite()), buffered write (handled by > __generic_file_aio_write()), and truncate (it can dirty last partial page - > handled by do_truncate()). Protect these places with sb_start_write() and > sb_end_write(). > > Signed-off-by: Jan Kara <jack@suse.cz> > --- > fs/buffer.c | 18 ++---------------- > fs/open.c | 6 ++++++ > mm/filemap.c | 3 ++- > 3 files changed, 10 insertions(+), 17 deletions(-) > > diff --git a/fs/buffer.c b/fs/buffer.c > index 19d8eb7..8519405 100644 > --- a/fs/buffer.c > +++ b/fs/buffer.c > @@ -2371,18 +2371,7 @@ int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, The comment for __block_page_mkwrite() needs to be updated to reference sb_start_write() and sb_end_write() instead of vfs_check_frozen(). Cheers, Andreas > 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; > - } > wait_on_page_writeback(page); > return 0; > out_unlock: > @@ -2397,12 +2386,9 @@ int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, > 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); > + sb_start_write(sb); > ret = __block_page_mkwrite(vma, vmf, get_block); > + sb_end_write(sb); > return block_page_mkwrite_return(ret); > } > EXPORT_SYMBOL(block_page_mkwrite); > diff --git a/fs/open.c b/fs/open.c > index 22c41b5..ee17c90 100644 > --- a/fs/open.c > +++ b/fs/open.c > @@ -55,8 +55,14 @@ int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs, > if (ret) > newattrs.ia_valid |= ret | ATTR_FORCE; > > + /* > + * Truncate can dirty last partial page so we need protection against > + * filesystem freezing. > + */ > mutex_lock(&dentry->d_inode->i_mutex); > + sb_start_write(dentry->d_sb); > ret = notify_change(dentry, &newattrs); > + sb_end_write(dentry->d_sb); > mutex_unlock(&dentry->d_inode->i_mutex); > return ret; > } > diff --git a/mm/filemap.c b/mm/filemap.c > index c0018f2..6566c73 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -2529,7 +2529,7 @@ ssize_t __generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, > count = ocount; > pos = *ppos; > > - vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); > + sb_start_write(inode->i_sb); > > /* We can write back this queue in page reclaim */ > current->backing_dev_info = mapping->backing_dev_info; > @@ -2601,6 +2601,7 @@ ssize_t __generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, > pos, ppos, count, written); > } > out: > + sb_end_write(inode->i_sb); > current->backing_dev_info = NULL; > return written ? written : err; > } > -- > 1.7.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu 12-01-12 12:56:01, Andreas Dilger wrote: > On 2012-01-11, at 6:20 PM, Jan Kara wrote: > > There are three entry points which dirty pages in a filesystem. mmap (handled > > by block_page_mkwrite()), buffered write (handled by > > __generic_file_aio_write()), and truncate (it can dirty last partial page - > > handled by do_truncate()). Protect these places with sb_start_write() and > > sb_end_write(). > > > > Signed-off-by: Jan Kara <jack@suse.cz> > > --- > > fs/buffer.c | 18 ++---------------- > > fs/open.c | 6 ++++++ > > mm/filemap.c | 3 ++- > > 3 files changed, 10 insertions(+), 17 deletions(-) > > > > diff --git a/fs/buffer.c b/fs/buffer.c > > index 19d8eb7..8519405 100644 > > --- a/fs/buffer.c > > +++ b/fs/buffer.c > > @@ -2371,18 +2371,7 @@ int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, > > The comment for __block_page_mkwrite() needs to be updated to reference > sb_start_write() and sb_end_write() instead of vfs_check_frozen(). Thanks. Fixed. Honza
diff --git a/fs/buffer.c b/fs/buffer.c index 19d8eb7..8519405 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -2371,18 +2371,7 @@ int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, 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; - } wait_on_page_writeback(page); return 0; out_unlock: @@ -2397,12 +2386,9 @@ int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, 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); + sb_start_write(sb); ret = __block_page_mkwrite(vma, vmf, get_block); + sb_end_write(sb); return block_page_mkwrite_return(ret); } EXPORT_SYMBOL(block_page_mkwrite); diff --git a/fs/open.c b/fs/open.c index 22c41b5..ee17c90 100644 --- a/fs/open.c +++ b/fs/open.c @@ -55,8 +55,14 @@ int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs, if (ret) newattrs.ia_valid |= ret | ATTR_FORCE; + /* + * Truncate can dirty last partial page so we need protection against + * filesystem freezing. + */ mutex_lock(&dentry->d_inode->i_mutex); + sb_start_write(dentry->d_sb); ret = notify_change(dentry, &newattrs); + sb_end_write(dentry->d_sb); mutex_unlock(&dentry->d_inode->i_mutex); return ret; } diff --git a/mm/filemap.c b/mm/filemap.c index c0018f2..6566c73 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2529,7 +2529,7 @@ ssize_t __generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, count = ocount; pos = *ppos; - vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); + sb_start_write(inode->i_sb); /* We can write back this queue in page reclaim */ current->backing_dev_info = mapping->backing_dev_info; @@ -2601,6 +2601,7 @@ ssize_t __generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, pos, ppos, count, written); } out: + sb_end_write(inode->i_sb); current->backing_dev_info = NULL; return written ? written : err; }
There are three entry points which dirty pages in a filesystem. mmap (handled by block_page_mkwrite()), buffered write (handled by __generic_file_aio_write()), and truncate (it can dirty last partial page - handled by do_truncate()). Protect these places with sb_start_write() and sb_end_write(). Signed-off-by: Jan Kara <jack@suse.cz> --- fs/buffer.c | 18 ++---------------- fs/open.c | 6 ++++++ mm/filemap.c | 3 ++- 3 files changed, 10 insertions(+), 17 deletions(-)