[PATCH] mm: more commenting on lock ordering
[powerpc.git] / mm / filemap.c
index c4fe97f..8558732 100644 (file)
@@ -75,8 +75,8 @@ generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
  *  ->mmap_sem
  *    ->lock_page              (access_process_vm)
  *
- *  ->mmap_sem
- *    ->i_mutex                        (msync)
+ *  ->i_mutex                  (generic_file_buffered_write)
+ *    ->mmap_sem               (fault_in_pages_readable->do_page_fault)
  *
  *  ->i_mutex
  *    ->i_alloc_sem             (various)
@@ -1139,23 +1139,24 @@ success:
 }
 
 /**
- * __generic_file_aio_read - generic filesystem read routine
+ * generic_file_aio_read - generic filesystem read routine
  * @iocb:      kernel I/O control block
  * @iov:       io vector request
  * @nr_segs:   number of segments in the iovec
- * @ppos:      current file position
+ * @pos:       current file position
  *
  * This is the "read()" routine for all filesystems
  * that can use the page cache directly.
  */
 ssize_t
-__generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
-               unsigned long nr_segs, loff_t *ppos)
+generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
+               unsigned long nr_segs, loff_t pos)
 {
        struct file *filp = iocb->ki_filp;
        ssize_t retval;
        unsigned long seg;
        size_t count;
+       loff_t *ppos = &iocb->ki_pos;
 
        count = 0;
        for (seg = 0; seg < nr_segs; seg++) {
@@ -1179,7 +1180,7 @@ __generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
 
        /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
        if (filp->f_flags & O_DIRECT) {
-               loff_t pos = *ppos, size;
+               loff_t size;
                struct address_space *mapping;
                struct inode *inode;
 
@@ -1197,8 +1198,10 @@ __generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
                        if (retval > 0)
                                *ppos = pos + retval;
                }
-               file_accessed(filp);
-               goto out;
+               if (likely(retval != 0)) {
+                       file_accessed(filp);
+                       goto out;
+               }
        }
 
        retval = 0;
@@ -1223,33 +1226,8 @@ __generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
 out:
        return retval;
 }
-EXPORT_SYMBOL(__generic_file_aio_read);
-
-ssize_t
-generic_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos)
-{
-       struct iovec local_iov = { .iov_base = buf, .iov_len = count };
-
-       BUG_ON(iocb->ki_pos != pos);
-       return __generic_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos);
-}
 EXPORT_SYMBOL(generic_file_aio_read);
 
-ssize_t
-generic_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
-{
-       struct iovec local_iov = { .iov_base = buf, .iov_len = count };
-       struct kiocb kiocb;
-       ssize_t ret;
-
-       init_sync_kiocb(&kiocb, filp);
-       ret = __generic_file_aio_read(&kiocb, &local_iov, 1, ppos);
-       if (-EIOCBQUEUED == ret)
-               ret = wait_on_sync_kiocb(&kiocb);
-       return ret;
-}
-EXPORT_SYMBOL(generic_file_read);
-
 int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size)
 {
        ssize_t written;
@@ -2244,7 +2222,7 @@ __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
                                unsigned long nr_segs, loff_t *ppos)
 {
        struct file *file = iocb->ki_filp;
-       const struct address_space * mapping = file->f_mapping;
+       struct address_space * mapping = file->f_mapping;
        size_t ocount;          /* original count */
        size_t count;           /* after file limit checks */
        struct inode    *inode = mapping->host;
@@ -2297,8 +2275,11 @@ __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
 
        /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
        if (unlikely(file->f_flags & O_DIRECT)) {
-               written = generic_file_direct_write(iocb, iov,
-                               &nr_segs, pos, ppos, count, ocount);
+               loff_t endbyte;
+               ssize_t written_buffered;
+
+               written = generic_file_direct_write(iocb, iov, &nr_segs, pos,
+                                                       ppos, count, ocount);
                if (written < 0 || written == count)
                        goto out;
                /*
@@ -2307,30 +2288,66 @@ __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
                 */
                pos += written;
                count -= written;
-       }
+               written_buffered = generic_file_buffered_write(iocb, iov,
+                                               nr_segs, pos, ppos, count,
+                                               written);
+               /*
+                * If generic_file_buffered_write() retuned a synchronous error
+                * then we want to return the number of bytes which were
+                * direct-written, or the error code if that was zero.  Note
+                * that this differs from normal direct-io semantics, which
+                * will return -EFOO even if some bytes were written.
+                */
+               if (written_buffered < 0) {
+                       err = written_buffered;
+                       goto out;
+               }
 
-       written = generic_file_buffered_write(iocb, iov, nr_segs,
-                       pos, ppos, count, written);
+               /*
+                * We need to ensure that the page cache pages are written to
+                * disk and invalidated to preserve the expected O_DIRECT
+                * semantics.
+                */
+               endbyte = pos + written_buffered - written - 1;
+               err = do_sync_file_range(file, pos, endbyte,
+                                        SYNC_FILE_RANGE_WAIT_BEFORE|
+                                        SYNC_FILE_RANGE_WRITE|
+                                        SYNC_FILE_RANGE_WAIT_AFTER);
+               if (err == 0) {
+                       written = written_buffered;
+                       invalidate_mapping_pages(mapping,
+                                                pos >> PAGE_CACHE_SHIFT,
+                                                endbyte >> PAGE_CACHE_SHIFT);
+               } else {
+                       /*
+                        * We don't know how much we wrote, so just return
+                        * the number of bytes which were direct-written
+                        */
+               }
+       } else {
+               written = generic_file_buffered_write(iocb, iov, nr_segs,
+                               pos, ppos, count, written);
+       }
 out:
        current->backing_dev_info = NULL;
        return written ? written : err;
 }
-EXPORT_SYMBOL(generic_file_aio_write_nolock);
 
-ssize_t
-generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
-                               unsigned long nr_segs, loff_t *ppos)
+ssize_t generic_file_aio_write_nolock(struct kiocb *iocb,
+               const struct iovec *iov, unsigned long nr_segs, loff_t pos)
 {
        struct file *file = iocb->ki_filp;
        struct address_space *mapping = file->f_mapping;
        struct inode *inode = mapping->host;
        ssize_t ret;
-       loff_t pos = *ppos;
 
-       ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, ppos);
+       BUG_ON(iocb->ki_pos != pos);
+
+       ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
+                       &iocb->ki_pos);
 
        if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
-               int err;
+               ssize_t err;
 
                err = sync_page_range_nolock(inode, mapping, pos, ret);
                if (err < 0)
@@ -2338,51 +2355,21 @@ generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
        }
        return ret;
 }
+EXPORT_SYMBOL(generic_file_aio_write_nolock);
 
-static ssize_t
-__generic_file_write_nolock(struct file *file, const struct iovec *iov,
-                               unsigned long nr_segs, loff_t *ppos)
-{
-       struct kiocb kiocb;
-       ssize_t ret;
-
-       init_sync_kiocb(&kiocb, file);
-       ret = __generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
-       if (ret == -EIOCBQUEUED)
-               ret = wait_on_sync_kiocb(&kiocb);
-       return ret;
-}
-
-ssize_t
-generic_file_write_nolock(struct file *file, const struct iovec *iov,
-                               unsigned long nr_segs, loff_t *ppos)
-{
-       struct kiocb kiocb;
-       ssize_t ret;
-
-       init_sync_kiocb(&kiocb, file);
-       ret = generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
-       if (-EIOCBQUEUED == ret)
-               ret = wait_on_sync_kiocb(&kiocb);
-       return ret;
-}
-EXPORT_SYMBOL(generic_file_write_nolock);
-
-ssize_t generic_file_aio_write(struct kiocb *iocb, const char __user *buf,
-                              size_t count, loff_t pos)
+ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
+               unsigned long nr_segs, loff_t pos)
 {
        struct file *file = iocb->ki_filp;
        struct address_space *mapping = file->f_mapping;
        struct inode *inode = mapping->host;
        ssize_t ret;
-       struct iovec local_iov = { .iov_base = (void __user *)buf,
-                                       .iov_len = count };
 
        BUG_ON(iocb->ki_pos != pos);
 
        mutex_lock(&inode->i_mutex);
-       ret = __generic_file_aio_write_nolock(iocb, &local_iov, 1,
-                                               &iocb->ki_pos);
+       ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
+                       &iocb->ki_pos);
        mutex_unlock(&inode->i_mutex);
 
        if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
@@ -2396,66 +2383,6 @@ ssize_t generic_file_aio_write(struct kiocb *iocb, const char __user *buf,
 }
 EXPORT_SYMBOL(generic_file_aio_write);
 
-ssize_t generic_file_write(struct file *file, const char __user *buf,
-                          size_t count, loff_t *ppos)
-{
-       struct address_space *mapping = file->f_mapping;
-       struct inode *inode = mapping->host;
-       ssize_t ret;
-       struct iovec local_iov = { .iov_base = (void __user *)buf,
-                                       .iov_len = count };
-
-       mutex_lock(&inode->i_mutex);
-       ret = __generic_file_write_nolock(file, &local_iov, 1, ppos);
-       mutex_unlock(&inode->i_mutex);
-
-       if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
-               ssize_t err;
-
-               err = sync_page_range(inode, mapping, *ppos - ret, ret);
-               if (err < 0)
-                       ret = err;
-       }
-       return ret;
-}
-EXPORT_SYMBOL(generic_file_write);
-
-ssize_t generic_file_readv(struct file *filp, const struct iovec *iov,
-                       unsigned long nr_segs, loff_t *ppos)
-{
-       struct kiocb kiocb;
-       ssize_t ret;
-
-       init_sync_kiocb(&kiocb, filp);
-       ret = __generic_file_aio_read(&kiocb, iov, nr_segs, ppos);
-       if (-EIOCBQUEUED == ret)
-               ret = wait_on_sync_kiocb(&kiocb);
-       return ret;
-}
-EXPORT_SYMBOL(generic_file_readv);
-
-ssize_t generic_file_writev(struct file *file, const struct iovec *iov,
-                       unsigned long nr_segs, loff_t *ppos)
-{
-       struct address_space *mapping = file->f_mapping;
-       struct inode *inode = mapping->host;
-       ssize_t ret;
-
-       mutex_lock(&inode->i_mutex);
-       ret = __generic_file_write_nolock(file, iov, nr_segs, ppos);
-       mutex_unlock(&inode->i_mutex);
-
-       if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
-               int err;
-
-               err = sync_page_range(inode, mapping, *ppos - ret, ret);
-               if (err < 0)
-                       ret = err;
-       }
-       return ret;
-}
-EXPORT_SYMBOL(generic_file_writev);
-
 /*
  * Called under i_mutex for writes to S_ISREG files.   Returns -EIO if something
  * went wrong during pagecache shootdown.