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@@ -1,7 +1,7 @@
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/**
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* attrib.c - NTFS attribute operations. Part of the Linux-NTFS project.
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*
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- * Copyright (c) 2001-2004 Anton Altaparmakov
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+ * Copyright (c) 2001-2005 Anton Altaparmakov
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* Copyright (c) 2002 Richard Russon
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*
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* This program/include file is free software; you can redistribute it and/or
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@@ -30,7 +30,7 @@
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#include "types.h"
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/**
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- * ntfs_map_runlist - map (a part of) a runlist of an ntfs inode
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+ * ntfs_map_runlist_nolock - map (a part of) a runlist of an ntfs inode
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* @ni: ntfs inode for which to map (part of) a runlist
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* @vcn: map runlist part containing this vcn
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*
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@@ -38,24 +38,23 @@
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*
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* Return 0 on success and -errno on error.
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*
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- * Locking: - The runlist must be unlocked on entry and is unlocked on return.
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- * - This function takes the lock for writing and modifies the runlist.
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+ * Locking: - The runlist must be locked for writing.
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+ * - This function modifies the runlist.
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*/
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-int ntfs_map_runlist(ntfs_inode *ni, VCN vcn)
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+int ntfs_map_runlist_nolock(ntfs_inode *ni, VCN vcn)
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{
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ntfs_inode *base_ni;
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- ntfs_attr_search_ctx *ctx;
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MFT_RECORD *mrec;
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+ ntfs_attr_search_ctx *ctx;
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+ runlist_element *rl;
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int err = 0;
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ntfs_debug("Mapping runlist part containing vcn 0x%llx.",
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(unsigned long long)vcn);
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-
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if (!NInoAttr(ni))
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base_ni = ni;
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else
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base_ni = ni->ext.base_ntfs_ino;
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-
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mrec = map_mft_record(base_ni);
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if (IS_ERR(mrec))
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return PTR_ERR(mrec);
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@@ -66,15 +65,7 @@ int ntfs_map_runlist(ntfs_inode *ni, VCN vcn)
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}
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err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
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CASE_SENSITIVE, vcn, NULL, 0, ctx);
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- if (unlikely(err))
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- goto put_err_out;
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-
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- down_write(&ni->runlist.lock);
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- /* Make sure someone else didn't do the work while we were sleeping. */
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- if (likely(ntfs_rl_vcn_to_lcn(ni->runlist.rl, vcn) <=
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- LCN_RL_NOT_MAPPED)) {
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- runlist_element *rl;
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-
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+ if (likely(!err)) {
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rl = ntfs_mapping_pairs_decompress(ni->vol, ctx->attr,
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ni->runlist.rl);
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if (IS_ERR(rl))
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@@ -82,9 +73,6 @@ int ntfs_map_runlist(ntfs_inode *ni, VCN vcn)
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else
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ni->runlist.rl = rl;
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}
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- up_write(&ni->runlist.lock);
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-
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-put_err_out:
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ntfs_attr_put_search_ctx(ctx);
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err_out:
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unmap_mft_record(base_ni);
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@@ -92,17 +80,45 @@ err_out:
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}
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/**
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- * ntfs_find_vcn - find a vcn in the runlist described by an ntfs inode
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- * @ni: ntfs inode describing the runlist to search
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- * @vcn: vcn to find
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- * @need_write: if false, lock for reading and if true, lock for writing
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+ * ntfs_map_runlist - map (a part of) a runlist of an ntfs inode
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+ * @ni: ntfs inode for which to map (part of) a runlist
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+ * @vcn: map runlist part containing this vcn
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+ *
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+ * Map the part of a runlist containing the @vcn of the ntfs inode @ni.
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+ *
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+ * Return 0 on success and -errno on error.
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+ *
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+ * Locking: - The runlist must be unlocked on entry and is unlocked on return.
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+ * - This function takes the runlist lock for writing and modifies the
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+ * runlist.
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+ */
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+int ntfs_map_runlist(ntfs_inode *ni, VCN vcn)
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+{
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+ int err = 0;
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+
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+ down_write(&ni->runlist.lock);
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+ /* Make sure someone else didn't do the work while we were sleeping. */
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+ if (likely(ntfs_rl_vcn_to_lcn(ni->runlist.rl, vcn) <=
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+ LCN_RL_NOT_MAPPED))
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+ err = ntfs_map_runlist_nolock(ni, vcn);
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+ up_write(&ni->runlist.lock);
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+ return err;
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+}
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+
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+/**
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+ * ntfs_find_vcn_nolock - find a vcn in the runlist described by an ntfs inode
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+ * @ni: ntfs inode describing the runlist to search
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+ * @vcn: vcn to find
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+ * @write_locked: true if the runlist is locked for writing
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*
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* Find the virtual cluster number @vcn in the runlist described by the ntfs
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* inode @ni and return the address of the runlist element containing the @vcn.
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- * The runlist is left locked and the caller has to unlock it. If @need_write
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- * is true, the runlist is locked for writing and if @need_write is false, the
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- * runlist is locked for reading. In the error case, the runlist is not left
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- * locked.
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+ * The runlist is left locked and the caller has to unlock it. In the error
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+ * case, the runlist is left in the same locking state as on entry.
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+ *
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+ * Note if @write_locked is FALSE the lock may be dropped inside the function
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+ * so you cannot rely on the runlist still being the same when this function
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+ * returns.
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*
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* Note you need to distinguish between the lcn of the returned runlist element
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* being >= 0 and LCN_HOLE. In the later case you have to return zeroes on
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@@ -124,28 +140,24 @@ err_out:
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* true, it is locked for writing. Otherwise is is locked for
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* reading.
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*/
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-runlist_element *ntfs_find_vcn(ntfs_inode *ni, const VCN vcn,
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- const BOOL need_write)
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+runlist_element *ntfs_find_vcn_nolock(ntfs_inode *ni, const VCN vcn,
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+ const BOOL write_locked)
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{
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runlist_element *rl;
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int err = 0;
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BOOL is_retry = FALSE;
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- ntfs_debug("Entering for i_ino 0x%lx, vcn 0x%llx, lock for %sing.",
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+ ntfs_debug("Entering for i_ino 0x%lx, vcn 0x%llx, %s_locked.",
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ni->mft_no, (unsigned long long)vcn,
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- !need_write ? "read" : "writ");
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+ write_locked ? "write" : "read");
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BUG_ON(!ni);
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BUG_ON(!NInoNonResident(ni));
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BUG_ON(vcn < 0);
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-lock_retry_remap:
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- if (!need_write)
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- down_read(&ni->runlist.lock);
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- else
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- down_write(&ni->runlist.lock);
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+retry_remap:
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rl = ni->runlist.rl;
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if (likely(rl && vcn >= rl[0].vcn)) {
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while (likely(rl->length)) {
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- if (likely(vcn < rl[1].vcn)) {
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+ if (unlikely(vcn < rl[1].vcn)) {
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if (likely(rl->lcn >= LCN_HOLE)) {
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ntfs_debug("Done.");
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return rl;
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@@ -161,19 +173,23 @@ lock_retry_remap:
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err = -EIO;
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}
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}
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- if (!need_write)
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- up_read(&ni->runlist.lock);
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- else
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- up_write(&ni->runlist.lock);
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if (!err && !is_retry) {
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/*
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* The @vcn is in an unmapped region, map the runlist and
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* retry.
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*/
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- err = ntfs_map_runlist(ni, vcn);
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+ if (!write_locked) {
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+ up_read(&ni->runlist.lock);
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+ down_write(&ni->runlist.lock);
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+ }
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+ err = ntfs_map_runlist_nolock(ni, vcn);
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+ if (!write_locked) {
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+ up_write(&ni->runlist.lock);
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+ down_read(&ni->runlist.lock);
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+ }
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if (likely(!err)) {
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is_retry = TRUE;
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- goto lock_retry_remap;
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+ goto retry_remap;
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}
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/*
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* -EINVAL and -ENOENT coming from a failed mapping attempt are
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@@ -184,7 +200,8 @@ lock_retry_remap:
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err = -EIO;
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} else if (!err)
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err = -EIO;
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- ntfs_error(ni->vol->sb, "Failed with error code %i.", err);
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+ if (err != -ENOENT)
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+ ntfs_error(ni->vol->sb, "Failed with error code %i.", err);
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return ERR_PTR(err);
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}
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Anton Altaparmakov