ext4: fix potential deadlock in ext4_nonda_switch()

[cascardo/linux.git] / fs / ext4 / inode.c

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 89b59cb..0a31197 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -233,6 +233,11 @@ void ext4_evict_inode(struct inode *inode)
        if (is_bad_inode(inode))
                goto no_delete;
 
+       /*
+        * Protect us against freezing - iput() caller didn't have to have any
+        * protection against it
+        */
+       sb_start_intwrite(inode->i_sb);
        handle = ext4_journal_start(inode, ext4_blocks_for_truncate(inode)+3);
        if (IS_ERR(handle)) {
                ext4_std_error(inode->i_sb, PTR_ERR(handle));
@@ -242,6 +247,7 @@ void ext4_evict_inode(struct inode *inode)
                 * cleaned up.
                 */
                ext4_orphan_del(NULL, inode);
+               sb_end_intwrite(inode->i_sb);
                goto no_delete;
        }
 
@@ -273,6 +279,7 @@ void ext4_evict_inode(struct inode *inode)
                stop_handle:
                        ext4_journal_stop(handle);
                        ext4_orphan_del(NULL, inode);
+                       sb_end_intwrite(inode->i_sb);
                        goto no_delete;
                }
        }
@@ -301,6 +308,7 @@ void ext4_evict_inode(struct inode *inode)
        else
                ext4_free_inode(handle, inode);
        ext4_journal_stop(handle);
+       sb_end_intwrite(inode->i_sb);
        return;
 no_delete:
        ext4_clear_inode(inode);        /* We must guarantee clearing of inode... */
@@ -724,11 +732,13 @@ struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
        err = ext4_map_blocks(handle, inode, &map,
                              create ? EXT4_GET_BLOCKS_CREATE : 0);
 
+       /* ensure we send some value back into *errp */
+       *errp = 0;
+
        if (err < 0)
                *errp = err;
        if (err <= 0)
                return NULL;
-       *errp = 0;
 
        bh = sb_getblk(inode->i_sb, map.m_pblk);
        if (!bh) {
@@ -1946,9 +1956,6 @@ out:
        return ret;
 }
 
-static int ext4_set_bh_endio(struct buffer_head *bh, struct inode *inode);
-static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate);
-
 /*
  * Note that we don't need to start a transaction unless we're journaling data
  * because we should have holes filled from ext4_page_mkwrite(). We even don't
@@ -2455,6 +2462,16 @@ static int ext4_nonda_switch(struct super_block *sb)
        free_blocks  = EXT4_C2B(sbi,
                percpu_counter_read_positive(&sbi->s_freeclusters_counter));
        dirty_blocks = percpu_counter_read_positive(&sbi->s_dirtyclusters_counter);
+       /*
+        * Start pushing delalloc when 1/2 of free blocks are dirty.
+        */
+       if (dirty_blocks && (free_blocks < 2 * dirty_blocks) &&
+           !writeback_in_progress(sb->s_bdi) &&
+           down_read_trylock(&sb->s_umount)) {
+               writeback_inodes_sb(sb, WB_REASON_FS_FREE_SPACE);
+               up_read(&sb->s_umount);
+       }
+
        if (2 * free_blocks < 3 * dirty_blocks ||
                free_blocks < (dirty_blocks + EXT4_FREECLUSTERS_WATERMARK)) {
                /*
@@ -2463,13 +2480,6 @@ static int ext4_nonda_switch(struct super_block *sb)
                 */
                return 1;
        }
-       /*
-        * Even if we don't switch but are nearing capacity,
-        * start pushing delalloc when 1/2 of free blocks are dirty.
-        */
-       if (free_blocks < 2 * dirty_blocks)
-               writeback_inodes_sb_if_idle(sb, WB_REASON_FS_FREE_SPACE);
-
        return 0;
 }
 
@@ -4779,11 +4789,7 @@ int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
        get_block_t *get_block;
        int retries = 0;
 
-       /*
-        * This check is racy but catches the common case. We rely on
-        * __block_page_mkwrite() to do a reliable check.
-        */
-       vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
+       sb_start_pagefault(inode->i_sb);
        /* Delalloc case is easy... */
        if (test_opt(inode->i_sb, DELALLOC) &&
            !ext4_should_journal_data(inode) &&
@@ -4851,5 +4857,6 @@ retry_alloc:
 out_ret:
        ret = block_page_mkwrite_return(ret);
 out:
+       sb_end_pagefault(inode->i_sb);
        return ret;
 }