NTFS: - Change {__,}ntfs_cluster_free() to also take an optional attribute
search context as argument. This allows calling it with the mft
record mapped. Update all callers.
- Fix potential deadlock in ntfs_mft_data_extend_allocation_nolock()
error handling by passing in the active search context when calling
ntfs_cluster_free().
Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
diff --git a/fs/ntfs/lcnalloc.h b/fs/ntfs/lcnalloc.h
index a6a8827..aa05185 100644
--- a/fs/ntfs/lcnalloc.h
+++ b/fs/ntfs/lcnalloc.h
@@ -27,6 +27,7 @@
#include <linux/fs.h>
+#include "attrib.h"
#include "types.h"
#include "inode.h"
#include "runlist.h"
@@ -44,13 +45,14 @@
const NTFS_CLUSTER_ALLOCATION_ZONES zone);
extern s64 __ntfs_cluster_free(ntfs_inode *ni, const VCN start_vcn,
- s64 count, const BOOL is_rollback);
+ s64 count, ntfs_attr_search_ctx *ctx, const BOOL is_rollback);
/**
* ntfs_cluster_free - free clusters on an ntfs volume
* @ni: ntfs inode whose runlist describes the clusters to free
* @start_vcn: vcn in the runlist of @ni at which to start freeing clusters
* @count: number of clusters to free or -1 for all clusters
+ * @ctx: active attribute search context if present or NULL if not
*
* Free @count clusters starting at the cluster @start_vcn in the runlist
* described by the ntfs inode @ni.
@@ -59,12 +61,36 @@
* deallocated. Thus, to completely free all clusters in a runlist, use
* @start_vcn = 0 and @count = -1.
*
- * Note, ntfs_cluster_free() does not modify the runlist at all, so the caller
- * has to deal with it later.
+ * If @ctx is specified, it is an active search context of @ni and its base mft
+ * record. This is needed when ntfs_cluster_free() encounters unmapped runlist
+ * fragments and allows their mapping. If you do not have the mft record
+ * mapped, you can specify @ctx as NULL and ntfs_cluster_free() will perform
+ * the necessary mapping and unmapping.
+ *
+ * Note, ntfs_cluster_free() saves the state of @ctx on entry and restores it
+ * before returning. Thus, @ctx will be left pointing to the same attribute on
+ * return as on entry. However, the actual pointers in @ctx may point to
+ * different memory locations on return, so you must remember to reset any
+ * cached pointers from the @ctx, i.e. after the call to ntfs_cluster_free(),
+ * you will probably want to do:
+ * m = ctx->mrec;
+ * a = ctx->attr;
+ * Assuming you cache ctx->attr in a variable @a of type ATTR_RECORD * and that
+ * you cache ctx->mrec in a variable @m of type MFT_RECORD *.
+ *
+ * Note, ntfs_cluster_free() does not modify the runlist, so you have to remove
+ * from the runlist or mark sparse the freed runs later.
*
* Return the number of deallocated clusters (not counting sparse ones) on
* success and -errno on error.
*
+ * WARNING: If @ctx is supplied, regardless of whether success or failure is
+ * returned, you need to check IS_ERR(@ctx->mrec) and if TRUE the @ctx
+ * is no longer valid, i.e. you need to either call
+ * ntfs_attr_reinit_search_ctx() or ntfs_attr_put_search_ctx() on it.
+ * In that case PTR_ERR(@ctx->mrec) will give you the error code for
+ * why the mapping of the old inode failed.
+ *
* Locking: - The runlist described by @ni must be locked for writing on entry
* and is locked on return. Note the runlist may be modified when
* needed runlist fragments need to be mapped.
@@ -72,11 +98,15 @@
* on return.
* - This function takes the volume lcn bitmap lock for writing and
* modifies the bitmap contents.
+ * - If @ctx is NULL, the base mft record of @ni must not be mapped on
+ * entry and it will be left unmapped on return.
+ * - If @ctx is not NULL, the base mft record must be mapped on entry
+ * and it will be left mapped on return.
*/
static inline s64 ntfs_cluster_free(ntfs_inode *ni, const VCN start_vcn,
- s64 count)
+ s64 count, ntfs_attr_search_ctx *ctx)
{
- return __ntfs_cluster_free(ni, start_vcn, count, FALSE);
+ return __ntfs_cluster_free(ni, start_vcn, count, ctx, FALSE);
}
extern int ntfs_cluster_free_from_rl_nolock(ntfs_volume *vol,