Btrfs: fix btrfs_ordered_update_i_size to update disk_i_size properly

btrfs_ordered_update_i_size can be called by truncate and endio, but
only endio takes ordered_extent which contains the completed IO.

while truncating down a file, if there are some in-flight IOs,
btrfs_ordered_update_i_size in endio will set disk_i_size to
@orig_offset that is zero.  If truncating-down fails somehow, we try to
recover in memory isize with this zero'd disk_i_size.

Fix it by only updating disk_i_size with @orig_offset when
btrfs_ordered_update_i_size is not called from endio while truncating
down and waiting for in-flight IOs completing their work before recover
in-memory size.

Besides fixing the above issue, add an assertion for last_size to double
check we truncate down to the desired size.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 4727b52..3944346 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4695,6 +4695,13 @@ error:
 
        btrfs_free_path(path);
 
+       if (err == 0) {
+               /* only inline file may have last_size != new_size */
+               if (new_size >= fs_info->sectorsize ||
+                   new_size > fs_info->max_inline)
+                       ASSERT(last_size == new_size);
+       }
+
        if (be_nice && bytes_deleted > SZ_32M) {
                unsigned long updates = trans->delayed_ref_updates;
                if (updates) {
@@ -5080,6 +5087,13 @@ static int btrfs_setsize(struct inode *inode, struct iattr *attr)
                if (ret && inode->i_nlink) {
                        int err;
 
+                       /* To get a stable disk_i_size */
+                       err = btrfs_wait_ordered_range(inode, 0, (u64)-1);
+                       if (err) {
+                               btrfs_orphan_del(NULL, inode);
+                               return err;
+                       }
+
                        /*
                         * failed to truncate, disk_i_size is only adjusted down
                         * as we remove extents, so it should represent the true

diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index 7ae350a..2cdf016 100644 (file)
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -984,8 +984,18 @@ int btrfs_ordered_update_i_size(struct inode *inode, u64 offset,
        }
        disk_i_size = BTRFS_I(inode)->disk_i_size;
 
-       /* truncate file */
-       if (disk_i_size > i_size) {
+       /*
+        * truncate file.
+        * If ordered is not NULL, then this is called from endio and
+        * disk_i_size will be updated by either truncate itself or any
+        * in-flight IOs which are inside the disk_i_size.
+        *
+        * Because btrfs_setsize() may set i_size with disk_i_size if truncate
+        * fails somehow, we need to make sure we have a precise disk_i_size by
+        * updating it as usual.
+        *
+        */
+       if (!ordered && disk_i_size > i_size) {
                BTRFS_I(inode)->disk_i_size = orig_offset;
                ret = 0;
                goto out;