UBIFS: fix zero-length truncations

Always allow truncations to zero, even if budgeting thinks there
is no space. UBIFS reserves some space for deletions anyway.

Otherwise, the following happans:
1. create a file, and write as much as possible there, until ENOSPC
2. truncate the file, which fails with ENOSPC, which is not good.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
index 5c96f1fb70166dbd75217692722d9e727be1d031..2b267c9a18065030ff8caff09fc6b2d5cc08b558 100644 (file)
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -587,7 +587,6 @@ static int ubifs_unlink(struct inode *dir, struct dentry *dentry)
        if (err) {
                if (err != -ENOSPC)
                        return err;
-               err = 0;
                budgeted = 0;
        }
 

diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
index 4071d1cae29f7cb0b65221ecd541b3832b37be31..3d698e2022b1ee7b2c8250fc75c89fff79785097 100644 (file)
--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -793,7 +793,7 @@ static int do_truncation(struct ubifs_info *c, struct inode *inode,
        int err;
        struct ubifs_budget_req req;
        loff_t old_size = inode->i_size, new_size = attr->ia_size;
-       int offset = new_size & (UBIFS_BLOCK_SIZE - 1);
+       int offset = new_size & (UBIFS_BLOCK_SIZE - 1), budgeted = 1;
        struct ubifs_inode *ui = ubifs_inode(inode);
 
        dbg_gen("ino %lu, size %lld -> %lld", inode->i_ino, old_size, new_size);
@@ -811,8 +811,15 @@ static int do_truncation(struct ubifs_info *c, struct inode *inode,
        /* A funny way to budget for truncation node */
        req.dirtied_ino_d = UBIFS_TRUN_NODE_SZ;
        err = ubifs_budget_space(c, &req);
-       if (err)
-               return err;
+       if (err) {
+               /*
+                * Treat truncations to zero as deletion and always allow them,
+                * just like we do for '->unlink()'.
+                */
+               if (new_size || err != -ENOSPC)
+                       return err;
+               budgeted = 0;
+       }
 
        err = vmtruncate(inode, new_size);
        if (err)
@@ -869,7 +876,12 @@ static int do_truncation(struct ubifs_info *c, struct inode *inode,
        err = ubifs_jnl_truncate(c, inode, old_size, new_size);
        mutex_unlock(&ui->ui_mutex);
 out_budg:
-       ubifs_release_budget(c, &req);
+       if (budgeted)
+               ubifs_release_budget(c, &req);
+       else {
+               c->nospace = c->nospace_rp = 0;
+               smp_wmb();
+       }
        return err;
 }