ocfs2: Wrap access of directory allocations with ip_alloc_sem.

OCFS2_I(inode)->ip_alloc_sem is a read-write semaphore protecting
local concurrent access of ocfs2 inodes.  However, ocfs2 directories were
not taking the semaphore while they accessed or modified the allocation
tree.

ocfs2_extend_dir() needs to take the semaphore in a write mode when it
adds to the allocation.  All other directory users get there via
ocfs2_bread(), which takes the semaphore in read mode.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

diff --git a/fs/ocfs2/dir.c b/fs/ocfs2/dir.c
index 67e6866a2a4fb0782b13050ccbe2e6402698036f..c441ef1f2badab7a2d8b2cc9cba5a0ac85ee9bb3 100644 (file)
--- a/fs/ocfs2/dir.c
+++ b/fs/ocfs2/dir.c
@@ -403,7 +403,7 @@ static int ocfs2_extend_dir(struct ocfs2_super *osb,
                            struct buffer_head **new_de_bh)
 {
        int status = 0;
-       int credits, num_free_extents;
+       int credits, num_free_extents, drop_alloc_sem = 0;
        loff_t dir_i_size;
        struct ocfs2_dinode *fe = (struct ocfs2_dinode *) parent_fe_bh->b_data;
        struct ocfs2_alloc_context *data_ac = NULL;
@@ -452,6 +452,9 @@ static int ocfs2_extend_dir(struct ocfs2_super *osb,
                credits = OCFS2_SIMPLE_DIR_EXTEND_CREDITS;
        }
 
+       down_write(&OCFS2_I(dir)->ip_alloc_sem);
+       drop_alloc_sem = 1;
+
        handle = ocfs2_start_trans(osb, credits);
        if (IS_ERR(handle)) {
                status = PTR_ERR(handle);
@@ -497,6 +500,8 @@ static int ocfs2_extend_dir(struct ocfs2_super *osb,
        *new_de_bh = new_bh;
        get_bh(*new_de_bh);
 bail:
+       if (drop_alloc_sem)
+               up_write(&OCFS2_I(dir)->ip_alloc_sem);
        if (handle)
                ocfs2_commit_trans(osb, handle);
 

diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index 21a605079c62328b5c2b9a4615f3f7bb444dee26..58ec54b60038ed47b1ce27f760dea386736f581c 100644 (file)
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -1106,8 +1106,10 @@ struct buffer_head *ocfs2_bread(struct inode *inode,
                return NULL;
        }
 
+       down_read(&OCFS2_I(inode)->ip_alloc_sem);
        tmperr = ocfs2_extent_map_get_blocks(inode, block, &p_blkno, NULL,
                                             NULL);
+       up_read(&OCFS2_I(inode)->ip_alloc_sem);
        if (tmperr < 0) {
                mlog_errno(tmperr);
                goto fail;