Add GETFSMAP support; some performance improvements for very large

file systems and for random write workloads into a preallocated file;
 bug fixes and cleanups.
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Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull ext4 updates from Ted Ts'o:

 - add GETFSMAP support

 - some performance improvements for very large file systems and for
   random write workloads into a preallocated file

 - bug fixes and cleanups.

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  jbd2: cleanup write flags handling from jbd2_write_superblock()
  ext4: mark superblock writes synchronous for nobarrier mounts
  ext4: inherit encryption xattr before other xattrs
  ext4: replace BUG_ON with WARN_ONCE in ext4_end_bio()
  ext4: avoid unnecessary transaction stalls during writeback
  ext4: preload block group descriptors
  ext4: make ext4_shutdown() static
  ext4: support GETFSMAP ioctls
  vfs: add common GETFSMAP ioctl definitions
  ext4: evict inline data when writing to memory map
  ext4: remove ext4_xattr_check_entry()
  ext4: rename ext4_xattr_check_names() to ext4_xattr_check_entries()
  ext4: merge ext4_xattr_list() into ext4_listxattr()
  ext4: constify static data that is never modified
  ext4: trim return value and 'dir' argument from ext4_insert_dentry()
  jbd2: fix dbench4 performance regression for 'nobarrier' mounts
  jbd2: Fix lockdep splat with generic/270 test
  mm: retry writepages() on ENOMEM when doing an data integrity writeback

fs/ext4/ioctl.c

@@ -19,6 +19,9 @@
 #include <linux/delay.h>
 #include "ext4_jbd2.h"
 #include "ext4.h"
+#include <linux/fsmap.h>
+#include "fsmap.h"
+#include <trace/events/ext4.h>
 
 /**
  * Swap memory between @a and @b for @len bytes.
@@ -443,7 +446,7 @@ static inline unsigned long ext4_xflags_to_iflags(__u32 xflags)
 	return iflags;
 }
 
-int ext4_shutdown(struct super_block *sb, unsigned long arg)
+static int ext4_shutdown(struct super_block *sb, unsigned long arg)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
 	__u32 flags;
@@ -489,6 +492,90 @@ int ext4_shutdown(struct super_block *sb, unsigned long arg)
 	return 0;
 }
 
+struct getfsmap_info {
+	struct super_block	*gi_sb;
+	struct fsmap_head __user *gi_data;
+	unsigned int		gi_idx;
+	__u32			gi_last_flags;
+};
+
+static int ext4_getfsmap_format(struct ext4_fsmap *xfm, void *priv)
+{
+	struct getfsmap_info *info = priv;
+	struct fsmap fm;
+
+	trace_ext4_getfsmap_mapping(info->gi_sb, xfm);
+
+	info->gi_last_flags = xfm->fmr_flags;
+	ext4_fsmap_from_internal(info->gi_sb, &fm, xfm);
+	if (copy_to_user(&info->gi_data->fmh_recs[info->gi_idx++], &fm,
+			sizeof(struct fsmap)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static int ext4_ioc_getfsmap(struct super_block *sb,
+			     struct fsmap_head __user *arg)
+{
+	struct getfsmap_info info = {0};
+	struct ext4_fsmap_head xhead = {0};
+	struct fsmap_head head;
+	bool aborted = false;
+	int error;
+
+	if (copy_from_user(&head, arg, sizeof(struct fsmap_head)))
+		return -EFAULT;
+	if (memchr_inv(head.fmh_reserved, 0, sizeof(head.fmh_reserved)) ||
+	    memchr_inv(head.fmh_keys[0].fmr_reserved, 0,
+		       sizeof(head.fmh_keys[0].fmr_reserved)) ||
+	    memchr_inv(head.fmh_keys[1].fmr_reserved, 0,
+		       sizeof(head.fmh_keys[1].fmr_reserved)))
+		return -EINVAL;
+	/*
+	 * ext4 doesn't report file extents at all, so the only valid
+	 * file offsets are the magic ones (all zeroes or all ones).
+	 */
+	if (head.fmh_keys[0].fmr_offset ||
+	    (head.fmh_keys[1].fmr_offset != 0 &&
+	     head.fmh_keys[1].fmr_offset != -1ULL))
+		return -EINVAL;
+
+	xhead.fmh_iflags = head.fmh_iflags;
+	xhead.fmh_count = head.fmh_count;
+	ext4_fsmap_to_internal(sb, &xhead.fmh_keys[0], &head.fmh_keys[0]);
+	ext4_fsmap_to_internal(sb, &xhead.fmh_keys[1], &head.fmh_keys[1]);
+
+	trace_ext4_getfsmap_low_key(sb, &xhead.fmh_keys[0]);
+	trace_ext4_getfsmap_high_key(sb, &xhead.fmh_keys[1]);
+
+	info.gi_sb = sb;
+	info.gi_data = arg;
+	error = ext4_getfsmap(sb, &xhead, ext4_getfsmap_format, &info);
+	if (error == EXT4_QUERY_RANGE_ABORT) {
+		error = 0;
+		aborted = true;
+	} else if (error)
+		return error;
+
+	/* If we didn't abort, set the "last" flag in the last fmx */
+	if (!aborted && info.gi_idx) {
+		info.gi_last_flags |= FMR_OF_LAST;
+		if (copy_to_user(&info.gi_data->fmh_recs[info.gi_idx - 1].fmr_flags,
+				 &info.gi_last_flags,
+				 sizeof(info.gi_last_flags)))
+			return -EFAULT;
+	}
+
+	/* copy back header */
+	head.fmh_entries = xhead.fmh_entries;
+	head.fmh_oflags = xhead.fmh_oflags;
+	if (copy_to_user(arg, &head, sizeof(struct fsmap_head)))
+		return -EFAULT;
+
+	return 0;
+}
+
 long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
 	struct inode *inode = file_inode(filp);
@@ -499,6 +586,8 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	ext4_debug("cmd = %u, arg = %lu\n", cmd, arg);
 
 	switch (cmd) {
+	case FS_IOC_GETFSMAP:
+		return ext4_ioc_getfsmap(sb, (void __user *)arg);
 	case EXT4_IOC_GETFLAGS:
 		flags = ei->i_flags & EXT4_FL_USER_VISIBLE;
 		return put_user(flags, (int __user *) arg);
@@ -1007,6 +1096,7 @@ long ext4_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	case EXT4_IOC_GET_ENCRYPTION_PWSALT:
 	case EXT4_IOC_GET_ENCRYPTION_POLICY:
 	case EXT4_IOC_SHUTDOWN:
+	case FS_IOC_GETFSMAP:
 		break;
 	default:
 		return -ENOIOCTLCMD;