NTFS: Add fs/ntfs/attrib.[hc]::ntfs_attr_vcn_to_lcn_nolock() used by the new
write code.
Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c
index fa464fc..1610f1c 100644
--- a/fs/ntfs/attrib.c
+++ b/fs/ntfs/attrib.c
@@ -106,6 +106,93 @@
}
/**
+ * ntfs_attr_vcn_to_lcn_nolock - convert a vcn into a lcn given an ntfs inode
+ * @ni: ntfs inode of the attribute whose runlist to search
+ * @vcn: vcn to convert
+ * @write_locked: true if the runlist is locked for writing
+ *
+ * Find the virtual cluster number @vcn in the runlist of the ntfs attribute
+ * described by the ntfs inode @ni and return the corresponding logical cluster
+ * number (lcn).
+ *
+ * If the @vcn is not mapped yet, the attempt is made to map the attribute
+ * extent containing the @vcn and the vcn to lcn conversion is retried.
+ *
+ * If @write_locked is true the caller has locked the runlist for writing and
+ * if false for reading.
+ *
+ * Since lcns must be >= 0, we use negative return codes with special meaning:
+ *
+ * Return code Meaning / Description
+ * ==========================================
+ * LCN_HOLE Hole / not allocated on disk.
+ * LCN_ENOENT There is no such vcn in the runlist, i.e. @vcn is out of bounds.
+ * LCN_ENOMEM Not enough memory to map runlist.
+ * LCN_EIO Critical error (runlist/file is corrupt, i/o error, etc).
+ *
+ * Locking: - The runlist must be locked on entry and is left locked on return.
+ * - If @write_locked is FALSE, i.e. the runlist is locked for reading,
+ * the lock may be dropped inside the function so you cannot rely on
+ * the runlist still being the same when this function returns.
+ */
+LCN ntfs_attr_vcn_to_lcn_nolock(ntfs_inode *ni, const VCN vcn,
+ const BOOL write_locked)
+{
+ LCN lcn;
+ BOOL is_retry = FALSE;
+
+ ntfs_debug("Entering for i_ino 0x%lx, vcn 0x%llx, %s_locked.",
+ ni->mft_no, (unsigned long long)vcn,
+ write_locked ? "write" : "read");
+ BUG_ON(!ni);
+ BUG_ON(!NInoNonResident(ni));
+ BUG_ON(vcn < 0);
+retry_remap:
+ /* Convert vcn to lcn. If that fails map the runlist and retry once. */
+ lcn = ntfs_rl_vcn_to_lcn(ni->runlist.rl, vcn);
+ if (likely(lcn >= LCN_HOLE)) {
+ ntfs_debug("Done, lcn 0x%llx.", (long long)lcn);
+ return lcn;
+ }
+ if (lcn != LCN_RL_NOT_MAPPED) {
+ if (lcn != LCN_ENOENT)
+ lcn = LCN_EIO;
+ } else if (!is_retry) {
+ int err;
+
+ if (!write_locked) {
+ up_read(&ni->runlist.lock);
+ down_write(&ni->runlist.lock);
+ if (unlikely(ntfs_rl_vcn_to_lcn(ni->runlist.rl, vcn) !=
+ LCN_RL_NOT_MAPPED)) {
+ up_write(&ni->runlist.lock);
+ down_read(&ni->runlist.lock);
+ goto retry_remap;
+ }
+ }
+ err = ntfs_map_runlist_nolock(ni, vcn);
+ if (!write_locked) {
+ up_write(&ni->runlist.lock);
+ down_read(&ni->runlist.lock);
+ }
+ if (likely(!err)) {
+ is_retry = TRUE;
+ goto retry_remap;
+ }
+ if (err == -ENOENT)
+ lcn = LCN_ENOENT;
+ else if (err == -ENOMEM)
+ lcn = LCN_ENOMEM;
+ else
+ lcn = LCN_EIO;
+ }
+ if (lcn != LCN_ENOENT)
+ ntfs_error(ni->vol->sb, "Failed with error code %lli.",
+ (long long)lcn);
+ return lcn;
+}
+
+/**
* ntfs_find_vcn_nolock - find a vcn in the runlist described by an ntfs inode
* @ni: ntfs inode describing the runlist to search
* @vcn: vcn to find