Revert "Revert "ext4: make __ext4_get_inode_loc plug""

This reverts commit 72dbcf72156641fde4d8ea401e977341bfd35a05.

Instead of waiting forever for entropy that may just not happen, we now
try to actively generate entropy when required, and are thus hopefully
avoiding the problem that caused the nice ext4 IO pattern fix to be
reverted.

So revert the revert.

Cc: Ahmed S. Darwish <darwish.07@gmail.com>
Cc: Ted Ts'o <tytso@mit.edu>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Alexander E. Patrakov <patrakov@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 006b7a2..420fe3d 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4586,6 +4586,7 @@ static int __ext4_get_inode_loc(struct inode *inode,
        struct buffer_head      *bh;
        struct super_block      *sb = inode->i_sb;
        ext4_fsblk_t            block;
+       struct blk_plug         plug;
        int                     inodes_per_block, inode_offset;
 
        iloc->bh = NULL;
@@ -4674,6 +4675,7 @@ make_io:
                 * If we need to do any I/O, try to pre-readahead extra
                 * blocks from the inode table.
                 */
+               blk_start_plug(&plug);
                if (EXT4_SB(sb)->s_inode_readahead_blks) {
                        ext4_fsblk_t b, end, table;
                        unsigned num;
@@ -4704,6 +4706,7 @@ make_io:
                get_bh(bh);
                bh->b_end_io = end_buffer_read_sync;
                submit_bh(REQ_OP_READ, REQ_META | REQ_PRIO, bh);
+               blk_finish_plug(&plug);
                wait_on_buffer(bh);
                if (!buffer_uptodate(bh)) {
                        EXT4_ERROR_INODE_BLOCK(inode, block,