Revert "Revert "ext4: make __ext4_get_inode_loc plug""

This reverts commit f7b8746e6b5bd70fb337ac1bf87ff6b633a3ea2f.

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 006b7a2070bf6869d2f7c42500eea135919def74..420fe3deed39702b93a5567dbebe77a8e4b6b992 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,