JFFS2: Add parameter to reserve disk space for root

[cascardo/linux.git] / fs / jffs2 / nodemgmt.c

diff --git a/fs/jffs2/nodemgmt.c b/fs/jffs2/nodemgmt.c
index 6784d1e..0c96eb5 100644 (file)
--- a/fs/jffs2/nodemgmt.c
+++ b/fs/jffs2/nodemgmt.c
@@ -18,6 +18,37 @@
 #include "nodelist.h"
 #include "debug.h"
 
+/*
+ * Check whether the user is allowed to write.
+ */
+static int jffs2_rp_can_write(struct jffs2_sb_info *c)
+{
+       uint32_t avail;
+       struct jffs2_mount_opts *opts = &c->mount_opts;
+
+       avail = c->dirty_size + c->free_size + c->unchecked_size +
+               c->erasing_size - c->resv_blocks_write * c->sector_size
+               - c->nospc_dirty_size;
+
+       if (avail < 2 * opts->rp_size)
+               jffs2_dbg(1, "rpsize %u, dirty_size %u, free_size %u, "
+                         "erasing_size %u, unchecked_size %u, "
+                         "nr_erasing_blocks %u, avail %u, resrv %u\n",
+                         opts->rp_size, c->dirty_size, c->free_size,
+                         c->erasing_size, c->unchecked_size,
+                         c->nr_erasing_blocks, avail, c->nospc_dirty_size);
+
+       if (avail > opts->rp_size)
+               return 1;
+
+       /* Always allow root */
+       if (capable(CAP_SYS_RESOURCE))
+               return 1;
+
+       jffs2_dbg(1, "forbid writing\n");
+       return 0;
+}
+
 /**
  *     jffs2_reserve_space - request physical space to write nodes to flash
  *     @c: superblock info
@@ -55,6 +86,15 @@ int jffs2_reserve_space(struct jffs2_sb_info *c, uint32_t minsize,
 
        spin_lock(&c->erase_completion_lock);
 
+       /*
+        * Check if the free space is greater then size of the reserved pool.
+        * If not, only allow root to proceed with writing.
+        */
+       if (prio != ALLOC_DELETION && !jffs2_rp_can_write(c)) {
+               ret = -ENOSPC;
+               goto out;
+       }
+
        /* this needs a little more thought (true <tglx> :)) */
        while(ret == -EAGAIN) {
                while(c->nr_free_blocks + c->nr_erasing_blocks < blocksneeded) {
@@ -158,6 +198,8 @@ int jffs2_reserve_space(struct jffs2_sb_info *c, uint32_t minsize,
                        jffs2_dbg(1, "%s(): ret is %d\n", __func__, ret);
                }
        }
+
+out:
        spin_unlock(&c->erase_completion_lock);
        if (!ret)
                ret = jffs2_prealloc_raw_node_refs(c, c->nextblock, 1);