diff options
Diffstat (limited to 'fs/ntfs/runlist.c')
| -rw-r--r-- | fs/ntfs/runlist.c | 374 |
1 files changed, 353 insertions, 21 deletions
diff --git a/fs/ntfs/runlist.c b/fs/ntfs/runlist.c index 758855b..f5b2ac9 100644 --- a/fs/ntfs/runlist.c +++ b/fs/ntfs/runlist.c @@ -35,7 +35,7 @@ static inline void ntfs_rl_mm(runlist_element *base, int dst, int src, int size) { if (likely((dst != src) && (size > 0))) - memmove(base + dst, base + src, size * sizeof (*base)); + memmove(base + dst, base + src, size * sizeof(*base)); } /** @@ -95,6 +95,51 @@ static inline runlist_element *ntfs_rl_realloc(runlist_element *rl, } /** + * ntfs_rl_realloc_nofail - Reallocate memory for runlists + * @rl: original runlist + * @old_size: number of runlist elements in the original runlist @rl + * @new_size: number of runlist elements we need space for + * + * As the runlists grow, more memory will be required. To prevent the + * kernel having to allocate and reallocate large numbers of small bits of + * memory, this function returns an entire page of memory. + * + * This function guarantees that the allocation will succeed. It will sleep + * for as long as it takes to complete the allocation. + * + * It is up to the caller to serialize access to the runlist @rl. + * + * N.B. If the new allocation doesn't require a different number of pages in + * memory, the function will return the original pointer. + * + * On success, return a pointer to the newly allocated, or recycled, memory. + * On error, return -errno. The following error codes are defined: + * -ENOMEM - Not enough memory to allocate runlist array. + * -EINVAL - Invalid parameters were passed in. + */ +static inline runlist_element *ntfs_rl_realloc_nofail(runlist_element *rl, + int old_size, int new_size) +{ + runlist_element *new_rl; + + old_size = PAGE_ALIGN(old_size * sizeof(*rl)); + new_size = PAGE_ALIGN(new_size * sizeof(*rl)); + if (old_size == new_size) + return rl; + + new_rl = ntfs_malloc_nofs_nofail(new_size); + BUG_ON(!new_rl); + + if (likely(rl != NULL)) { + if (unlikely(old_size > new_size)) + old_size = new_size; + memcpy(new_rl, rl, old_size); + ntfs_free(rl); + } + return new_rl; +} + +/** * ntfs_are_rl_mergeable - test if two runlists can be joined together * @dst: original runlist * @src: new runlist to test for mergeability with @dst @@ -497,6 +542,7 @@ runlist_element *ntfs_runlists_merge(runlist_element *drl, /* Scan to the end of the source runlist. */ for (dend = 0; likely(drl[dend].length); dend++) ; + dend++; drl = ntfs_rl_realloc(drl, dend, dend + 1); if (IS_ERR(drl)) return drl; @@ -566,8 +612,8 @@ runlist_element *ntfs_runlists_merge(runlist_element *drl, ((drl[dins].vcn + drl[dins].length) <= /* End of hole */ (srl[send - 1].vcn + srl[send - 1].length))); - /* Or we'll lose an end marker */ - if (start && finish && (drl[dins].length == 0)) + /* Or we will lose an end marker. */ + if (finish && !drl[dins].length) ss++; if (marker && (drl[dins].vcn + drl[dins].length > srl[send - 1].vcn)) finish = FALSE; @@ -621,11 +667,8 @@ runlist_element *ntfs_runlists_merge(runlist_element *drl, if (drl[ds].lcn != LCN_RL_NOT_MAPPED) { /* Add an unmapped runlist element. */ if (!slots) { - /* FIXME/TODO: We need to have the - * extra memory already! (AIA) */ - drl = ntfs_rl_realloc(drl, ds, ds + 2); - if (!drl) - goto critical_error; + drl = ntfs_rl_realloc_nofail(drl, ds, + ds + 2); slots = 2; } ds++; @@ -640,13 +683,8 @@ runlist_element *ntfs_runlists_merge(runlist_element *drl, drl[ds].length = marker_vcn - drl[ds].vcn; /* Finally add the ENOENT terminator. */ ds++; - if (!slots) { - /* FIXME/TODO: We need to have the extra - * memory already! (AIA) */ - drl = ntfs_rl_realloc(drl, ds, ds + 1); - if (!drl) - goto critical_error; - } + if (!slots) + drl = ntfs_rl_realloc_nofail(drl, ds, ds + 1); drl[ds].vcn = marker_vcn; drl[ds].lcn = LCN_ENOENT; drl[ds].length = (s64)0; @@ -659,11 +697,6 @@ finished: ntfs_debug("Merged runlist:"); ntfs_debug_dump_runlist(drl); return drl; - -critical_error: - /* Critical error! We cannot afford to fail here. */ - ntfs_error(NULL, "Critical error! Not enough memory."); - panic("NTFS: Cannot continue."); } /** @@ -727,6 +760,9 @@ runlist_element *ntfs_mapping_pairs_decompress(const ntfs_volume *vol, ntfs_error(vol->sb, "Corrupt attribute."); return ERR_PTR(-EIO); } + /* If the mapping pairs array is valid but empty, nothing to do. */ + if (!vcn && !*buf) + return old_rl; /* Current position in runlist array. */ rlpos = 0; /* Allocate first page and set current runlist size to one page. */ @@ -1419,6 +1455,7 @@ err_out: /** * ntfs_rl_truncate_nolock - truncate a runlist starting at a specified vcn + * @vol: ntfs volume (needed for error output) * @runlist: runlist to truncate * @new_length: the new length of the runlist in VCNs * @@ -1426,12 +1463,16 @@ err_out: * holding the runlist elements to a length of @new_length VCNs. * * If @new_length lies within the runlist, the runlist elements with VCNs of - * @new_length and above are discarded. + * @new_length and above are discarded. As a special case if @new_length is + * zero, the runlist is discarded and set to NULL. * * If @new_length lies beyond the runlist, a sparse runlist element is added to * the end of the runlist @runlist or if the last runlist element is a sparse * one already, this is extended. * + * Note, no checking is done for unmapped runlist elements. It is assumed that + * the caller has mapped any elements that need to be mapped already. + * * Return 0 on success and -errno on error. * * Locking: The caller must hold @runlist->lock for writing. @@ -1446,6 +1487,13 @@ int ntfs_rl_truncate_nolock(const ntfs_volume *vol, runlist *const runlist, BUG_ON(!runlist); BUG_ON(new_length < 0); rl = runlist->rl; + if (!new_length) { + ntfs_debug("Freeing runlist."); + runlist->rl = NULL; + if (rl) + ntfs_free(rl); + return 0; + } if (unlikely(!rl)) { /* * Create a runlist consisting of a sparse runlist element of @@ -1553,4 +1601,288 @@ int ntfs_rl_truncate_nolock(const ntfs_volume *vol, runlist *const runlist, return 0; } +/** + * ntfs_rl_punch_nolock - punch a hole into a runlist + * @vol: ntfs volume (needed for error output) + * @runlist: runlist to punch a hole into + * @start: starting VCN of the hole to be created + * @length: size of the hole to be created in units of clusters + * + * Punch a hole into the runlist @runlist starting at VCN @start and of size + * @length clusters. + * + * Return 0 on success and -errno on error, in which case @runlist has not been + * modified. + * + * If @start and/or @start + @length are outside the runlist return error code + * -ENOENT. + * + * If the runlist contains unmapped or error elements between @start and @start + * + @length return error code -EINVAL. + * + * Locking: The caller must hold @runlist->lock for writing. + */ +int ntfs_rl_punch_nolock(const ntfs_volume *vol, runlist *const runlist, + const VCN start, const s64 length) +{ + const VCN end = start + length; + s64 delta; + runlist_element *rl, *rl_end, *rl_real_end, *trl; + int old_size; + BOOL lcn_fixup = FALSE; + + ntfs_debug("Entering for start 0x%llx, length 0x%llx.", + (long long)start, (long long)length); + BUG_ON(!runlist); + BUG_ON(start < 0); + BUG_ON(length < 0); + BUG_ON(end < 0); + rl = runlist->rl; + if (unlikely(!rl)) { + if (likely(!start && !length)) + return 0; + return -ENOENT; + } + /* Find @start in the runlist. */ + while (likely(rl->length && start >= rl[1].vcn)) + rl++; + rl_end = rl; + /* Find @end in the runlist. */ + while (likely(rl_end->length && end >= rl_end[1].vcn)) { + /* Verify there are no unmapped or error elements. */ + if (unlikely(rl_end->lcn < LCN_HOLE)) + return -EINVAL; + rl_end++; + } + /* Check the last element. */ + if (unlikely(rl_end->length && rl_end->lcn < LCN_HOLE)) + return -EINVAL; + /* This covers @start being out of bounds, too. */ + if (!rl_end->length && end > rl_end->vcn) + return -ENOENT; + if (!length) + return 0; + if (!rl->length) + return -ENOENT; + rl_real_end = rl_end; + /* Determine the runlist size. */ + while (likely(rl_real_end->length)) + rl_real_end++; + old_size = rl_real_end - runlist->rl + 1; + /* If @start is in a hole simply extend the hole. */ + if (rl->lcn == LCN_HOLE) { + /* + * If both @start and @end are in the same sparse run, we are + * done. + */ + if (end <= rl[1].vcn) { + ntfs_debug("Done (requested hole is already sparse)."); + return 0; + } +extend_hole: + /* Extend the hole. */ + rl->length = end - rl->vcn; + /* If @end is in a hole, merge it with the current one. */ + if (rl_end->lcn == LCN_HOLE) { + rl_end++; + rl->length = rl_end->vcn - rl->vcn; + } + /* We have done the hole. Now deal with the remaining tail. */ + rl++; + /* Cut out all runlist elements up to @end. */ + if (rl < rl_end) + memmove(rl, rl_end, (rl_real_end - rl_end + 1) * + sizeof(*rl)); + /* Adjust the beginning of the tail if necessary. */ + if (end > rl->vcn) { + s64 delta = end - rl->vcn; + rl->vcn = end; + rl->length -= delta; + /* Only adjust the lcn if it is real. */ + if (rl->lcn >= 0) + rl->lcn += delta; + } +shrink_allocation: + /* Reallocate memory if the allocation changed. */ + if (rl < rl_end) { + rl = ntfs_rl_realloc(runlist->rl, old_size, + old_size - (rl_end - rl)); + if (IS_ERR(rl)) + ntfs_warning(vol->sb, "Failed to shrink " + "runlist buffer. This just " + "wastes a bit of memory " + "temporarily so we ignore it " + "and return success."); + else + runlist->rl = rl; + } + ntfs_debug("Done (extend hole)."); + return 0; + } + /* + * If @start is at the beginning of a run things are easier as there is + * no need to split the first run. + */ + if (start == rl->vcn) { + /* + * @start is at the beginning of a run. + * + * If the previous run is sparse, extend its hole. + * + * If @end is not in the same run, switch the run to be sparse + * and extend the newly created hole. + * + * Thus both of these cases reduce the problem to the above + * case of "@start is in a hole". + */ + if (rl > runlist->rl && (rl - 1)->lcn == LCN_HOLE) { + rl--; + goto extend_hole; + } + if (end >= rl[1].vcn) { + rl->lcn = LCN_HOLE; + goto extend_hole; + } + /* + * The final case is when @end is in the same run as @start. + * For this need to split the run into two. One run for the + * sparse region between the beginning of the old run, i.e. + * @start, and @end and one for the remaining non-sparse + * region, i.e. between @end and the end of the old run. + */ + trl = ntfs_rl_realloc(runlist->rl, old_size, old_size + 1); + if (IS_ERR(trl)) + goto enomem_out; + old_size++; + if (runlist->rl != trl) { + rl = trl + (rl - runlist->rl); + rl_end = trl + (rl_end - runlist->rl); + rl_real_end = trl + (rl_real_end - runlist->rl); + runlist->rl = trl; + } +split_end: + /* Shift all the runs up by one. */ + memmove(rl + 1, rl, (rl_real_end - rl + 1) * sizeof(*rl)); + /* Finally, setup the two split runs. */ + rl->lcn = LCN_HOLE; + rl->length = length; + rl++; + rl->vcn += length; + /* Only adjust the lcn if it is real. */ + if (rl->lcn >= 0 || lcn_fixup) + rl->lcn += length; + rl->length -= length; + ntfs_debug("Done (split one)."); + return 0; + } + /* + * @start is neither in a hole nor at the beginning of a run. + * + * If @end is in a hole, things are easier as simply truncating the run + * @start is in to end at @start - 1, deleting all runs after that up + * to @end, and finally extending the beginning of the run @end is in + * to be @start is all that is needed. + */ + if (rl_end->lcn == LCN_HOLE) { + /* Truncate the run containing @start. */ + rl->length = start - rl->vcn; + rl++; + /* Cut out all runlist elements up to @end. */ + if (rl < rl_end) + memmove(rl, rl_end, (rl_real_end - rl_end + 1) * + sizeof(*rl)); + /* Extend the beginning of the run @end is in to be @start. */ + rl->vcn = start; + rl->length = rl[1].vcn - start; + goto shrink_allocation; + } + /* + * If @end is not in a hole there are still two cases to distinguish. + * Either @end is or is not in the same run as @start. + * + * The second case is easier as it can be reduced to an already solved + * problem by truncating the run @start is in to end at @start - 1. + * Then, if @end is in the next run need to split the run into a sparse + * run followed by a non-sparse run (already covered above) and if @end + * is not in the next run switching it to be sparse, again reduces the + * problem to the already covered case of "@start is in a hole". + */ + if (end >= rl[1].vcn) { + /* + * If @end is not in the next run, reduce the problem to the + * case of "@start is in a hole". + */ + if (rl[1].length && end >= rl[2].vcn) { + /* Truncate the run containing @start. */ + rl->length = start - rl->vcn; + rl++; + rl->vcn = start; + rl->lcn = LCN_HOLE; + goto extend_hole; + } + trl = ntfs_rl_realloc(runlist->rl, old_size, old_size + 1); + if (IS_ERR(trl)) + goto enomem_out; + old_size++; + if (runlist->rl != trl) { + rl = trl + (rl - runlist->rl); + rl_end = trl + (rl_end - runlist->rl); + rl_real_end = trl + (rl_real_end - runlist->rl); + runlist->rl = trl; + } + /* Truncate the run containing @start. */ + rl->length = start - rl->vcn; + rl++; + /* + * @end is in the next run, reduce the problem to the case + * where "@start is at the beginning of a run and @end is in + * the same run as @start". + */ + delta = rl->vcn - start; + rl->vcn = start; + if (rl->lcn >= 0) { + rl->lcn -= delta; + /* Need this in case the lcn just became negative. */ + lcn_fixup = TRUE; + } + rl->length += delta; + goto split_end; + } + /* + * The first case from above, i.e. @end is in the same run as @start. + * We need to split the run into three. One run for the non-sparse + * region between the beginning of the old run and @start, one for the + * sparse region between @start and @end, and one for the remaining + * non-sparse region, i.e. between @end and the end of the old run. + */ + trl = ntfs_rl_realloc(runlist->rl, old_size, old_size + 2); + if (IS_ERR(trl)) + goto enomem_out; + old_size += 2; + if (runlist->rl != trl) { + rl = trl + (rl - runlist->rl); + rl_end = trl + (rl_end - runlist->rl); + rl_real_end = trl + (rl_real_end - runlist->rl); + runlist->rl = trl; + } + /* Shift all the runs up by two. */ + memmove(rl + 2, rl, (rl_real_end - rl + 1) * sizeof(*rl)); + /* Finally, setup the three split runs. */ + rl->length = start - rl->vcn; + rl++; + rl->vcn = start; + rl->lcn = LCN_HOLE; + rl->length = length; + rl++; + delta = end - rl->vcn; + rl->vcn = end; + rl->lcn += delta; + rl->length -= delta; + ntfs_debug("Done (split both)."); + return 0; +enomem_out: + ntfs_error(vol->sb, "Not enough memory to extend runlist buffer."); + return -ENOMEM; +} + #endif /* NTFS_RW */ |
