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Diffstat (limited to 'fs/ntfs/runlist.c')
| -rw-r--r-- | fs/ntfs/runlist.c | 1438 |
1 files changed, 1438 insertions, 0 deletions
diff --git a/fs/ntfs/runlist.c b/fs/ntfs/runlist.c new file mode 100644 index 0000000..8438fb1 --- /dev/null +++ b/fs/ntfs/runlist.c @@ -0,0 +1,1438 @@ +/** + * runlist.c - NTFS runlist handling code. Part of the Linux-NTFS project. + * + * Copyright (c) 2001-2004 Anton Altaparmakov + * Copyright (c) 2002 Richard Russon + * + * This program/include file is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as published + * by the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program/include file is distributed in the hope that it will be + * useful, but WITHOUT ANY WARRANTY; without even the implied warranty + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program (in the main directory of the Linux-NTFS + * distribution in the file COPYING); if not, write to the Free Software + * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#include "debug.h" +#include "dir.h" +#include "endian.h" +#include "malloc.h" +#include "ntfs.h" + +/** + * ntfs_rl_mm - runlist memmove + * + * It is up to the caller to serialize access to the runlist @base. + */ +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)); +} + +/** + * ntfs_rl_mc - runlist memory copy + * + * It is up to the caller to serialize access to the runlists @dstbase and + * @srcbase. + */ +static inline void ntfs_rl_mc(runlist_element *dstbase, int dst, + runlist_element *srcbase, int src, int size) +{ + if (likely(size > 0)) + memcpy(dstbase + dst, srcbase + src, size * sizeof(*dstbase)); +} + +/** + * ntfs_rl_realloc - 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 and entire page of memory. + * + * 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(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(new_size); + if (unlikely(!new_rl)) + return ERR_PTR(-ENOMEM); + + 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 + * + * Test if two runlists can be joined together. For this, their VCNs and LCNs + * must be adjacent. + * + * It is up to the caller to serialize access to the runlists @dst and @src. + * + * Return: TRUE Success, the runlists can be merged. + * FALSE Failure, the runlists cannot be merged. + */ +static inline BOOL ntfs_are_rl_mergeable(runlist_element *dst, + runlist_element *src) +{ + BUG_ON(!dst); + BUG_ON(!src); + + if ((dst->lcn < 0) || (src->lcn < 0)) /* Are we merging holes? */ + return FALSE; + if ((dst->lcn + dst->length) != src->lcn) /* Are the runs contiguous? */ + return FALSE; + if ((dst->vcn + dst->length) != src->vcn) /* Are the runs misaligned? */ + return FALSE; + + return TRUE; +} + +/** + * __ntfs_rl_merge - merge two runlists without testing if they can be merged + * @dst: original, destination runlist + * @src: new runlist to merge with @dst + * + * Merge the two runlists, writing into the destination runlist @dst. The + * caller must make sure the runlists can be merged or this will corrupt the + * destination runlist. + * + * It is up to the caller to serialize access to the runlists @dst and @src. + */ +static inline void __ntfs_rl_merge(runlist_element *dst, runlist_element *src) +{ + dst->length += src->length; +} + +/** + * ntfs_rl_append - append a runlist after a given element + * @dst: original runlist to be worked on + * @dsize: number of elements in @dst (including end marker) + * @src: runlist to be inserted into @dst + * @ssize: number of elements in @src (excluding end marker) + * @loc: append the new runlist @src after this element in @dst + * + * Append the runlist @src after element @loc in @dst. Merge the right end of + * the new runlist, if necessary. Adjust the size of the hole before the + * appended runlist. + * + * It is up to the caller to serialize access to the runlists @dst and @src. + * + * On success, return a pointer to the new, combined, runlist. Note, both + * runlists @dst and @src are deallocated before returning so you cannot use + * the pointers for anything any more. (Strictly speaking the returned runlist + * may be the same as @dst but this is irrelevant.) + * + * On error, return -errno. Both runlists are left unmodified. 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_append(runlist_element *dst, + int dsize, runlist_element *src, int ssize, int loc) +{ + BOOL right; + int magic; + + BUG_ON(!dst); + BUG_ON(!src); + + /* First, check if the right hand end needs merging. */ + right = ntfs_are_rl_mergeable(src + ssize - 1, dst + loc + 1); + + /* Space required: @dst size + @src size, less one if we merged. */ + dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - right); + if (IS_ERR(dst)) + return dst; + /* + * We are guaranteed to succeed from here so can start modifying the + * original runlists. + */ + + /* First, merge the right hand end, if necessary. */ + if (right) + __ntfs_rl_merge(src + ssize - 1, dst + loc + 1); + + magic = loc + ssize; + + /* Move the tail of @dst out of the way, then copy in @src. */ + ntfs_rl_mm(dst, magic + 1, loc + 1 + right, dsize - loc - 1 - right); + ntfs_rl_mc(dst, loc + 1, src, 0, ssize); + + /* Adjust the size of the preceding hole. */ + dst[loc].length = dst[loc + 1].vcn - dst[loc].vcn; + + /* We may have changed the length of the file, so fix the end marker */ + if (dst[magic + 1].lcn == LCN_ENOENT) + dst[magic + 1].vcn = dst[magic].vcn + dst[magic].length; + + return dst; +} + +/** + * ntfs_rl_insert - insert a runlist into another + * @dst: original runlist to be worked on + * @dsize: number of elements in @dst (including end marker) + * @src: new runlist to be inserted + * @ssize: number of elements in @src (excluding end marker) + * @loc: insert the new runlist @src before this element in @dst + * + * Insert the runlist @src before element @loc in the runlist @dst. Merge the + * left end of the new runlist, if necessary. Adjust the size of the hole + * after the inserted runlist. + * + * It is up to the caller to serialize access to the runlists @dst and @src. + * + * On success, return a pointer to the new, combined, runlist. Note, both + * runlists @dst and @src are deallocated before returning so you cannot use + * the pointers for anything any more. (Strictly speaking the returned runlist + * may be the same as @dst but this is irrelevant.) + * + * On error, return -errno. Both runlists are left unmodified. 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_insert(runlist_element *dst, + int dsize, runlist_element *src, int ssize, int loc) +{ + BOOL left = FALSE; + BOOL disc = FALSE; /* Discontinuity */ + BOOL hole = FALSE; /* Following a hole */ + int magic; + + BUG_ON(!dst); + BUG_ON(!src); + + /* disc => Discontinuity between the end of @dst and the start of @src. + * This means we might need to insert a hole. + * hole => @dst ends with a hole or an unmapped region which we can + * extend to match the discontinuity. */ + if (loc == 0) + disc = (src[0].vcn > 0); + else { + s64 merged_length; + + left = ntfs_are_rl_mergeable(dst + loc - 1, src); + + merged_length = dst[loc - 1].length; + if (left) + merged_length += src->length; + + disc = (src[0].vcn > dst[loc - 1].vcn + merged_length); + if (disc) + hole = (dst[loc - 1].lcn == LCN_HOLE); + } + + /* Space required: @dst size + @src size, less one if we merged, plus + * one if there was a discontinuity, less one for a trailing hole. */ + dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - left + disc - hole); + if (IS_ERR(dst)) + return dst; + /* + * We are guaranteed to succeed from here so can start modifying the + * original runlist. + */ + + if (left) + __ntfs_rl_merge(dst + loc - 1, src); + + magic = loc + ssize - left + disc - hole; + + /* Move the tail of @dst out of the way, then copy in @src. */ + ntfs_rl_mm(dst, magic, loc, dsize - loc); + ntfs_rl_mc(dst, loc + disc - hole, src, left, ssize - left); + + /* Adjust the VCN of the last run ... */ + if (dst[magic].lcn <= LCN_HOLE) + dst[magic].vcn = dst[magic - 1].vcn + dst[magic - 1].length; + /* ... and the length. */ + if (dst[magic].lcn == LCN_HOLE || dst[magic].lcn == LCN_RL_NOT_MAPPED) + dst[magic].length = dst[magic + 1].vcn - dst[magic].vcn; + + /* Writing beyond the end of the file and there's a discontinuity. */ + if (disc) { + if (hole) + dst[loc - 1].length = dst[loc].vcn - dst[loc - 1].vcn; + else { + if (loc > 0) { + dst[loc].vcn = dst[loc - 1].vcn + + dst[loc - 1].length; + dst[loc].length = dst[loc + 1].vcn - + dst[loc].vcn; + } else { + dst[loc].vcn = 0; + dst[loc].length = dst[loc + 1].vcn; + } + dst[loc].lcn = LCN_RL_NOT_MAPPED; + } + + magic += hole; + + if (dst[magic].lcn == LCN_ENOENT) + dst[magic].vcn = dst[magic - 1].vcn + + dst[magic - 1].length; + } + return dst; +} + +/** + * ntfs_rl_replace - overwrite a runlist element with another runlist + * @dst: original runlist to be worked on + * @dsize: number of elements in @dst (including end marker) + * @src: new runlist to be inserted + * @ssize: number of elements in @src (excluding end marker) + * @loc: index in runlist @dst to overwrite with @src + * + * Replace the runlist element @dst at @loc with @src. Merge the left and + * right ends of the inserted runlist, if necessary. + * + * It is up to the caller to serialize access to the runlists @dst and @src. + * + * On success, return a pointer to the new, combined, runlist. Note, both + * runlists @dst and @src are deallocated before returning so you cannot use + * the pointers for anything any more. (Strictly speaking the returned runlist + * may be the same as @dst but this is irrelevant.) + * + * On error, return -errno. Both runlists are left unmodified. 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_replace(runlist_element *dst, + int dsize, runlist_element *src, int ssize, int loc) +{ + BOOL left = FALSE; + BOOL right; + int magic; + + BUG_ON(!dst); + BUG_ON(!src); + + /* First, merge the left and right ends, if necessary. */ + right = ntfs_are_rl_mergeable(src + ssize - 1, dst + loc + 1); + if (loc > 0) + left = ntfs_are_rl_mergeable(dst + loc - 1, src); + + /* Allocate some space. We'll need less if the left, right, or both + * ends were merged. */ + dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - left - right); + if (IS_ERR(dst)) + return dst; + /* + * We are guaranteed to succeed from here so can start modifying the + * original runlists. + */ + if (right) + __ntfs_rl_merge(src + ssize - 1, dst + loc + 1); + if (left) + __ntfs_rl_merge(dst + loc - 1, src); + + /* FIXME: What does this mean? (AIA) */ + magic = loc + ssize - left; + + /* Move the tail of @dst out of the way, then copy in @src. */ + ntfs_rl_mm(dst, magic, loc + right + 1, dsize - loc - right - 1); + ntfs_rl_mc(dst, loc, src, left, ssize - left); + + /* We may have changed the length of the file, so fix the end marker */ + if (dst[magic].lcn == LCN_ENOENT) + dst[magic].vcn = dst[magic - 1].vcn + dst[magic - 1].length; + return dst; +} + +/** + * ntfs_rl_split - insert a runlist into the centre of a hole + * @dst: original runlist to be worked on + * @dsize: number of elements in @dst (including end marker) + * @src: new runlist to be inserted + * @ssize: number of elements in @src (excluding end marker) + * @loc: index in runlist @dst at which to split and insert @src + * + * Split the runlist @dst at @loc into two and insert @new in between the two + * fragments. No merging of runlists is necessary. Adjust the size of the + * holes either side. + * + * It is up to the caller to serialize access to the runlists @dst and @src. + * + * On success, return a pointer to the new, combined, runlist. Note, both + * runlists @dst and @src are deallocated before returning so you cannot use + * the pointers for anything any more. (Strictly speaking the returned runlist + * may be the same as @dst but this is irrelevant.) + * + * On error, return -errno. Both runlists are left unmodified. 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_split(runlist_element *dst, int dsize, + runlist_element *src, int ssize, int loc) +{ + BUG_ON(!dst); + BUG_ON(!src); + + /* Space required: @dst size + @src size + one new hole. */ + dst = ntfs_rl_realloc(dst, dsize, dsize + ssize + 1); + if (IS_ERR(dst)) + return dst; + /* + * We are guaranteed to succeed from here so can start modifying the + * original runlists. + */ + + /* Move the tail of @dst out of the way, then copy in @src. */ + ntfs_rl_mm(dst, loc + 1 + ssize, loc, dsize - loc); + ntfs_rl_mc(dst, loc + 1, src, 0, ssize); + + /* Adjust the size of the holes either size of @src. */ + dst[loc].length = dst[loc+1].vcn - dst[loc].vcn; + dst[loc+ssize+1].vcn = dst[loc+ssize].vcn + dst[loc+ssize].length; + dst[loc+ssize+1].length = dst[loc+ssize+2].vcn - dst[loc+ssize+1].vcn; + + return dst; +} + +/** + * ntfs_runlists_merge - merge two runlists into one + * @drl: original runlist to be worked on + * @srl: new runlist to be merged into @drl + * + * First we sanity check the two runlists @srl and @drl to make sure that they + * are sensible and can be merged. The runlist @srl must be either after the + * runlist @drl or completely within a hole (or unmapped region) in @drl. + * + * It is up to the caller to serialize access to the runlists @drl and @srl. + * + * Merging of runlists is necessary in two cases: + * 1. When attribute lists are used and a further extent is being mapped. + * 2. When new clusters are allocated to fill a hole or extend a file. + * + * There are four possible ways @srl can be merged. It can: + * - be inserted at the beginning of a hole, + * - split the hole in two and be inserted between the two fragments, + * - be appended at the end of a hole, or it can + * - replace the whole hole. + * It can also be appended to the end of the runlist, which is just a variant + * of the insert case. + * + * On success, return a pointer to the new, combined, runlist. Note, both + * runlists @drl and @srl are deallocated before returning so you cannot use + * the pointers for anything any more. (Strictly speaking the returned runlist + * may be the same as @dst but this is irrelevant.) + * + * On error, return -errno. Both runlists are left unmodified. The following + * error codes are defined: + * -ENOMEM - Not enough memory to allocate runlist array. + * -EINVAL - Invalid parameters were passed in. + * -ERANGE - The runlists overlap and cannot be merged. + */ +runlist_element *ntfs_runlists_merge(runlist_element *drl, + runlist_element *srl) +{ + int di, si; /* Current index into @[ds]rl. */ + int sstart; /* First index with lcn > LCN_RL_NOT_MAPPED. */ + int dins; /* Index into @drl at which to insert @srl. */ + int dend, send; /* Last index into @[ds]rl. */ + int dfinal, sfinal; /* The last index into @[ds]rl with + lcn >= LCN_HOLE. */ + int marker = 0; + VCN marker_vcn = 0; + +#ifdef DEBUG + ntfs_debug("dst:"); + ntfs_debug_dump_runlist(drl); + ntfs_debug("src:"); + ntfs_debug_dump_runlist(srl); +#endif + + /* Check for silly calling... */ + if (unlikely(!srl)) + return drl; + if (IS_ERR(srl) || IS_ERR(drl)) + return ERR_PTR(-EINVAL); + + /* Check for the case where the first mapping is being done now. */ + if (unlikely(!drl)) { + drl = srl; + /* Complete the source runlist if necessary. */ + if (unlikely(drl[0].vcn)) { + /* Scan to the end of the source runlist. */ + for (dend = 0; likely(drl[dend].length); dend++) + ; + drl = ntfs_rl_realloc(drl, dend, dend + 1); + if (IS_ERR(drl)) + return drl; + /* Insert start element at the front of the runlist. */ + ntfs_rl_mm(drl, 1, 0, dend); + drl[0].vcn = 0; + drl[0].lcn = LCN_RL_NOT_MAPPED; + drl[0].length = drl[1].vcn; + } + goto finished; + } + + si = di = 0; + + /* Skip any unmapped start element(s) in the source runlist. */ + while (srl[si].length && srl[si].lcn < LCN_HOLE) + si++; + + /* Can't have an entirely unmapped source runlist. */ + BUG_ON(!srl[si].length); + + /* Record the starting points. */ + sstart = si; + + /* + * Skip forward in @drl until we reach the position where @srl needs to + * be inserted. If we reach the end of @drl, @srl just needs to be + * appended to @drl. + */ + for (; drl[di].length; di++) { + if (drl[di].vcn + drl[di].length > srl[sstart].vcn) + break; + } + dins = di; + + /* Sanity check for illegal overlaps. */ + if ((drl[di].vcn == srl[si].vcn) && (drl[di].lcn >= 0) && + (srl[si].lcn >= 0)) { + ntfs_error(NULL, "Run lists overlap. Cannot merge!"); + return ERR_PTR(-ERANGE); + } + + /* Scan to the end of both runlists in order to know their sizes. */ + for (send = si; srl[send].length; send++) + ; + for (dend = di; drl[dend].length; dend++) + ; + + if (srl[send].lcn == LCN_ENOENT) + marker_vcn = srl[marker = send].vcn; + + /* Scan to the last element with lcn >= LCN_HOLE. */ + for (sfinal = send; sfinal >= 0 && srl[sfinal].lcn < LCN_HOLE; sfinal--) + ; + for (dfinal = dend; dfinal >= 0 && drl[dfinal].lcn < LCN_HOLE; dfinal--) + ; + + { + BOOL start; + BOOL finish; + int ds = dend + 1; /* Number of elements in drl & srl */ + int ss = sfinal - sstart + 1; + + start = ((drl[dins].lcn < LCN_RL_NOT_MAPPED) || /* End of file */ + (drl[dins].vcn == srl[sstart].vcn)); /* Start of hole */ + finish = ((drl[dins].lcn >= LCN_RL_NOT_MAPPED) && /* End of file */ + ((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)) + ss++; + if (marker && (drl[dins].vcn + drl[dins].length > srl[send - 1].vcn)) + finish = FALSE; +#if 0 + ntfs_debug("dfinal = %i, dend = %i", dfinal, dend); + ntfs_debug("sstart = %i, sfinal = %i, send = %i", sstart, sfinal, send); + ntfs_debug("start = %i, finish = %i", start, finish); + ntfs_debug("ds = %i, ss = %i, dins = %i", ds, ss, dins); +#endif + if (start) { + if (finish) + drl = ntfs_rl_replace(drl, ds, srl + sstart, ss, dins); + else + drl = ntfs_rl_insert(drl, ds, srl + sstart, ss, dins); + } else { + if (finish) + drl = ntfs_rl_append(drl, ds, srl + sstart, ss, dins); + else + drl = ntfs_rl_split(drl, ds, srl + sstart, ss, dins); + } + if (IS_ERR(drl)) { + ntfs_error(NULL, "Merge failed."); + return drl; + } + ntfs_free(srl); + if (marker) { + ntfs_debug("Triggering marker code."); + for (ds = dend; drl[ds].length; ds++) + ; + /* We only need to care if @srl ended after @drl. */ + if (drl[ds].vcn <= marker_vcn) { + int slots = 0; + + if (drl[ds].vcn == marker_vcn) { + ntfs_debug("Old marker = 0x%llx, replacing " + "with LCN_ENOENT.", + (unsigned long long) + drl[ds].lcn); + drl[ds].lcn = LCN_ENOENT; + goto finished; + } + /* + * We need to create an unmapped runlist element in + * @drl or extend an existing one before adding the + * ENOENT terminator. + */ + if (drl[ds].lcn == LCN_ENOENT) { + ds--; + slots = 1; + } + 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; + slots = 2; + } + ds++; + /* Need to set vcn if it isn't set already. */ + if (slots != 1) + drl[ds].vcn = drl[ds - 1].vcn + + drl[ds - 1].length; + drl[ds].lcn = LCN_RL_NOT_MAPPED; + /* We now used up a slot. */ + slots--; + } + 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; + } + drl[ds].vcn = marker_vcn; + drl[ds].lcn = LCN_ENOENT; + drl[ds].length = (s64)0; + } + } + } + +finished: + /* The merge was completed successfully. */ + 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."); +} + +/** + * ntfs_mapping_pairs_decompress - convert mapping pairs array to runlist + * @vol: ntfs volume on which the attribute resides + * @attr: attribute record whose mapping pairs array to decompress + * @old_rl: optional runlist in which to insert @attr's runlist + * + * It is up to the caller to serialize access to the runlist @old_rl. + * + * Decompress the attribute @attr's mapping pairs array into a runlist. On + * success, return the decompressed runlist. + * + * If @old_rl is not NULL, decompressed runlist is inserted into the + * appropriate place in @old_rl and the resultant, combined runlist is + * returned. The original @old_rl is deallocated. + * + * On error, return -errno. @old_rl is left unmodified in that case. + * + * The following error codes are defined: + * -ENOMEM - Not enough memory to allocate runlist array. + * -EIO - Corrupt runlist. + * -EINVAL - Invalid parameters were passed in. + * -ERANGE - The two runlists overlap. + * + * FIXME: For now we take the conceptionally simplest approach of creating the + * new runlist disregarding the already existing one and then splicing the + * two into one, if that is possible (we check for overlap and discard the new + * runlist if overlap present before returning ERR_PTR(-ERANGE)). + */ +runlist_element *ntfs_mapping_pairs_decompress(const ntfs_volume *vol, + const ATTR_RECORD *attr, runlist_element *old_rl) +{ + VCN vcn; /* Current vcn. */ + LCN lcn; /* Current lcn. */ + s64 deltaxcn; /* Change in [vl]cn. */ + runlist_element *rl; /* The output runlist. */ + u8 *buf; /* Current position in mapping pairs array. */ + u8 *attr_end; /* End of attribute. */ + int rlsize; /* Size of runlist buffer. */ + u16 rlpos; /* Current runlist position in units of + runlist_elements. */ + u8 b; /* Current byte offset in buf. */ + +#ifdef DEBUG + /* Make sure attr exists and is non-resident. */ + if (!attr || !attr->non_resident || sle64_to_cpu( + attr->data.non_resident.lowest_vcn) < (VCN)0) { + ntfs_error(vol->sb, "Invalid arguments."); + return ERR_PTR(-EINVAL); + } +#endif + /* Start at vcn = lowest_vcn and lcn 0. */ + vcn = sle64_to_cpu(attr->data.non_resident.lowest_vcn); + lcn = 0; + /* Get start of the mapping pairs array. */ + buf = (u8*)attr + le16_to_cpu( + attr->data.non_resident.mapping_pairs_offset); + attr_end = (u8*)attr + le32_to_cpu(attr->length); + if (unlikely(buf < (u8*)attr || buf > attr_end)) { + ntfs_error(vol->sb, "Corrupt attribute."); + return ERR_PTR(-EIO); + } + /* Current position in runlist array. */ + rlpos = 0; + /* Allocate first page and set current runlist size to one page. */ + rl = ntfs_malloc_nofs(rlsize = PAGE_SIZE); + if (unlikely(!rl)) + return ERR_PTR(-ENOMEM); + /* Insert unmapped starting element if necessary. */ + if (vcn) { + rl->vcn = 0; + rl->lcn = LCN_RL_NOT_MAPPED; + rl->length = vcn; + rlpos++; + } + while (buf < attr_end && *buf) { + /* + * Allocate more memory if needed, including space for the + * not-mapped and terminator elements. ntfs_malloc_nofs() + * operates on whole pages only. + */ + if (((rlpos + 3) * sizeof(*old_rl)) > rlsize) { + runlist_element *rl2; + + rl2 = ntfs_malloc_nofs(rlsize + (int)PAGE_SIZE); + if (unlikely(!rl2)) { + ntfs_free(rl); + return ERR_PTR(-ENOMEM); + } + memcpy(rl2, rl, rlsize); + ntfs_free(rl); + rl = rl2; + rlsize += PAGE_SIZE; + } + /* Enter the current vcn into the current runlist element. */ + rl[rlpos].vcn = vcn; + /* + * Get the change in vcn, i.e. the run length in clusters. + * Doing it this way ensures that we signextend negative values. + * A negative run length doesn't make any sense, but hey, I + * didn't make up the NTFS specs and Windows NT4 treats the run + * length as a signed value so that's how it is... + */ + b = *buf & 0xf; + if (b) { + if (unlikely(buf + b > attr_end)) + goto io_error; + for (deltaxcn = (s8)buf[b--]; b; b--) + deltaxcn = (deltaxcn << 8) + buf[b]; + } else { /* The length entry is compulsory. */ + ntfs_error(vol->sb, "Missing length entry in mapping " + "pairs array."); + deltaxcn = (s64)-1; + } + /* + * Assume a negative length to indicate data corruption and + * hence clean-up and return NULL. + */ + if (unlikely(deltaxcn < 0)) { + ntfs_error(vol->sb, "Invalid length in mapping pairs " + "array."); + goto err_out; + } + /* + * Enter the current run length into the current runlist + * element. + */ + rl[rlpos].length = deltaxcn; + /* Increment the current vcn by the current run length. */ + vcn += deltaxcn; + /* + * There might be no lcn change at all, as is the case for + * sparse clusters on NTFS 3.0+, in which case we set the lcn + * to LCN_HOLE. + */ + if (!(*buf & 0xf0)) + rl[rlpos].lcn = LCN_HOLE; + else { + /* Get the lcn change which really can be negative. */ + u8 b2 = *buf & 0xf; + b = b2 + ((*buf >> 4) & 0xf); + if (buf + b > attr_end) + goto io_error; + for (deltaxcn = (s8)buf[b--]; b > b2; b--) + deltaxcn = (deltaxcn << 8) + buf[b]; + /* Change the current lcn to its new value. */ + lcn += deltaxcn; +#ifdef DEBUG + /* + * On NTFS 1.2-, apparently can have lcn == -1 to + * indicate a hole. But we haven't verified ourselves + * whether it is really the lcn or the deltaxcn that is + * -1. So if either is found give us a message so we + * can investigate it further! + */ + if (vol->major_ver < 3) { + if (unlikely(deltaxcn == (LCN)-1)) + ntfs_error(vol->sb, "lcn delta == -1"); + if (unlikely(lcn == (LCN)-1)) + ntfs_error(vol->sb, "lcn == -1"); + } +#endif + /* Check lcn is not below -1. */ + if (unlikely(lcn < (LCN)-1)) { + ntfs_error(vol->sb, "Invalid LCN < -1 in " + "mapping pairs array."); + goto err_out; + } + /* Enter the current lcn into the runlist element. */ + rl[rlpos].lcn = lcn; + } + /* Get to the next runlist element. */ + rlpos++; + /* Increment the buffer position to the next mapping pair. */ + buf += (*buf & 0xf) + ((*buf >> 4) & 0xf) + 1; + } + if (unlikely(buf >= attr_end)) + goto io_error; + /* + * If there is a highest_vcn specified, it must be equal to the final + * vcn in the runlist - 1, or something has gone badly wrong. + */ + deltaxcn = sle64_to_cpu(attr->data.non_resident.highest_vcn); + if (unlikely(deltaxcn && vcn - 1 != deltaxcn)) { +mpa_err: + ntfs_error(vol->sb, "Corrupt mapping pairs array in " + "non-resident attribute."); + goto err_out; + } + /* Setup not mapped runlist element if this is the base extent. */ + if (!attr->data.non_resident.lowest_vcn) { + VCN max_cluster; + + max_cluster = (sle64_to_cpu( + attr->data.non_resident.allocated_size) + + vol->cluster_size - 1) >> + vol->cluster_size_bits; + /* + * If there is a difference between the highest_vcn and the + * highest cluster, the runlist is either corrupt or, more + * likely, there are more extents following this one. + */ + if (deltaxcn < --max_cluster) { + ntfs_debug("More extents to follow; deltaxcn = 0x%llx, " + "max_cluster = 0x%llx", + (unsigned long long)deltaxcn, + (unsigned long long)max_cluster); + rl[rlpos].vcn = vcn; + vcn += rl[rlpos].length = max_cluster - deltaxcn; + rl[rlpos].lcn = LCN_RL_NOT_MAPPED; + rlpos++; + } else if (unlikely(deltaxcn > max_cluster)) { + ntfs_error(vol->sb, "Corrupt attribute. deltaxcn = " + "0x%llx, max_cluster = 0x%llx", + (unsigned long long)deltaxcn, + (unsigned long long)max_cluster); + goto mpa_err; + } + rl[rlpos].lcn = LCN_ENOENT; + } else /* Not the base extent. There may be more extents to follow. */ + rl[rlpos].lcn = LCN_RL_NOT_MAPPED; + + /* Setup terminating runlist element. */ + rl[rlpos].vcn = vcn; + rl[rlpos].length = (s64)0; + /* If no existing runlist was specified, we are done. */ + if (!old_rl) { + ntfs_debug("Mapping pairs array successfully decompressed:"); + ntfs_debug_dump_runlist(rl); + return rl; + } + /* Now combine the new and old runlists checking for overlaps. */ + old_rl = ntfs_runlists_merge(old_rl, rl); + if (likely(!IS_ERR(old_rl))) + return old_rl; + ntfs_free(rl); + ntfs_error(vol->sb, "Failed to merge runlists."); + return old_rl; +io_error: + ntfs_error(vol->sb, "Corrupt attribute."); +err_out: + ntfs_free(rl); + return ERR_PTR(-EIO); +} + +/** + * ntfs_rl_vcn_to_lcn - convert a vcn into a lcn given a runlist + * @rl: runlist to use for conversion + * @vcn: vcn to convert + * + * Convert the virtual cluster number @vcn of an attribute into a logical + * cluster number (lcn) of a device using the runlist @rl to map vcns to their + * corresponding lcns. + * + * It is up to the caller to serialize access to the runlist @rl. + * + * Since lcns must be >= 0, we use negative return values with special meaning: + * + * Return value Meaning / Description + * ================================================== + * -1 = LCN_HOLE Hole / not allocated on disk. + * -2 = LCN_RL_NOT_MAPPED This is part of the runlist which has not been + * inserted into the runlist yet. + * -3 = LCN_ENOENT There is no such vcn in the attribute. + * + * Locking: - The caller must have locked the runlist (for reading or writing). + * - This function does not touch the lock. + */ +LCN ntfs_rl_vcn_to_lcn(const runlist_element *rl, const VCN vcn) +{ + int i; + + BUG_ON(vcn < 0); + /* + * If rl is NULL, assume that we have found an unmapped runlist. The + * caller can then attempt to map it and fail appropriately if + * necessary. + */ + if (unlikely(!rl)) + return LCN_RL_NOT_MAPPED; + + /* Catch out of lower bounds vcn. */ + if (unlikely(vcn < rl[0].vcn)) + return LCN_ENOENT; + + for (i = 0; likely(rl[i].length); i++) { + if (unlikely(vcn < rl[i+1].vcn)) { + if (likely(rl[i].lcn >= (LCN)0)) + return rl[i].lcn + (vcn - rl[i].vcn); + return rl[i].lcn; + } + } + /* + * The terminator element is setup to the correct value, i.e. one of + * LCN_HOLE, LCN_RL_NOT_MAPPED, or LCN_ENOENT. + */ + if (likely(rl[i].lcn < (LCN)0)) + return rl[i].lcn; + /* Just in case... We could replace this with BUG() some day. */ + return LCN_ENOENT; +} + +/** + * ntfs_get_nr_significant_bytes - get number of bytes needed to store a number + * @n: number for which to get the number of bytes for + * + * Return the number of bytes required to store @n unambiguously as + * a signed number. + * + * This is used in the context of the mapping pairs array to determine how + * many bytes will be needed in the array to store a given logical cluster + * number (lcn) or a specific run length. + * + * Return the number of bytes written. This function cannot fail. + */ +static inline int ntfs_get_nr_significant_bytes(const s64 n) +{ + s64 l = n; + int i; + s8 j; + + i = 0; + do { + l >>= 8; + i++; + } while (l != 0 && l != -1); + j = (n >> 8 * (i - 1)) & 0xff; + /* If the sign bit is wrong, we need an extra byte. */ + if ((n < 0 && j >= 0) || (n > 0 && j < 0)) + i++; + return i; +} + +/** + * ntfs_get_size_for_mapping_pairs - get bytes needed for mapping pairs array + * @vol: ntfs volume (needed for the ntfs version) + * @rl: locked runlist to determine the size of the mapping pairs of + * @start_vcn: vcn at which to start the mapping pairs array + * + * Walk the locked runlist @rl and calculate the size in bytes of the mapping + * pairs array corresponding to the runlist @rl, starting at vcn @start_vcn. + * This for example allows us to allocate a buffer of the right size when + * building the mapping pairs array. + * + * If @rl is NULL, just return 1 (for the single terminator byte). + * + * Return the calculated size in bytes on success. On error, return -errno. + * The following error codes are defined: + * -EINVAL - Run list contains unmapped elements. Make sure to only pass + * fully mapped runlists to this function. + * -EIO - The runlist is corrupt. + * + * Locking: @rl must be locked on entry (either for reading or writing), it + * remains locked throughout, and is left locked upon return. + */ +int ntfs_get_size_for_mapping_pairs(const ntfs_volume *vol, + const runlist_element *rl, const VCN start_vcn) +{ + LCN prev_lcn; + int rls; + + BUG_ON(start_vcn < 0); + if (!rl) { + BUG_ON(start_vcn); + return 1; + } + /* Skip to runlist element containing @start_vcn. */ + while (rl->length && start_vcn >= rl[1].vcn) + rl++; + if ((!rl->length && start_vcn > rl->vcn) || start_vcn < rl->vcn) + return -EINVAL; + prev_lcn = 0; + /* Always need the termining zero byte. */ + rls = 1; + /* Do the first partial run if present. */ + if (start_vcn > rl->vcn) { + s64 delta; + + /* We know rl->length != 0 already. */ + if (rl->length < 0 || rl->lcn < LCN_HOLE) + goto err_out; + delta = start_vcn - rl->vcn; + /* Header byte + length. */ + rls += 1 + ntfs_get_nr_significant_bytes(rl->length - delta); + /* + * If the logical cluster number (lcn) denotes a hole and we + * are on NTFS 3.0+, we don't store it at all, i.e. we need + * zero space. On earlier NTFS versions we just store the lcn. + * Note: this assumes that on NTFS 1.2-, holes are stored with + * an lcn of -1 and not a delta_lcn of -1 (unless both are -1). + */ + if (rl->lcn >= 0 || vol->major_ver < 3) { + prev_lcn = rl->lcn; + if (rl->lcn >= 0) + prev_lcn += delta; + /* Change in lcn. */ + rls += ntfs_get_nr_significant_bytes(prev_lcn); + } + /* Go to next runlist element. */ + rl++; + } + /* Do the full runs. */ + for (; rl->length; rl++) { + if (rl->length < 0 || rl->lcn < LCN_HOLE) + goto err_out; + /* Header byte + length. */ + rls += 1 + ntfs_get_nr_significant_bytes(rl->length); + /* + * If the logical cluster number (lcn) denotes a hole and we + * are on NTFS 3.0+, we don't store it at all, i.e. we need + * zero space. On earlier NTFS versions we just store the lcn. + * Note: this assumes that on NTFS 1.2-, holes are stored with + * an lcn of -1 and not a delta_lcn of -1 (unless both are -1). + */ + if (rl->lcn >= 0 || vol->major_ver < 3) { + /* Change in lcn. */ + rls += ntfs_get_nr_significant_bytes(rl->lcn - + prev_lcn); + prev_lcn = rl->lcn; + } + } + return rls; +err_out: + if (rl->lcn == LCN_RL_NOT_MAPPED) + rls = -EINVAL; + else + rls = -EIO; + return rls; +} + +/** + * ntfs_write_significant_bytes - write the significant bytes of a number + * @dst: destination buffer to write to + * @dst_max: pointer to last byte of destination buffer for bounds checking + * @n: number whose significant bytes to write + * + * Store in @dst, the minimum bytes of the number @n which are required to + * identify @n unambiguously as a signed number, taking care not to exceed + * @dest_max, the maximum position within @dst to which we are allowed to + * write. + * + * This is used when building the mapping pairs array of a runlist to compress + * a given logical cluster number (lcn) or a specific run length to the minumum + * size possible. + * + * Return the number of bytes written on success. On error, i.e. the + * destination buffer @dst is too small, return -ENOSPC. + */ +static inline int ntfs_write_significant_bytes(s8 *dst, const s8 *dst_max, + const s64 n) +{ + s64 l = n; + int i; + s8 j; + + i = 0; + do { + if (dst > dst_max) + goto err_out; + *dst++ = l & 0xffll; + l >>= 8; + i++; + } while (l != 0 && l != -1); + j = (n >> 8 * (i - 1)) & 0xff; + /* If the sign bit is wrong, we need an extra byte. */ + if (n < 0 && j >= 0) { + if (dst > dst_max) + goto err_out; + i++; + *dst = (s8)-1; + } else if (n > 0 && j < 0) { + if (dst > dst_max) + goto err_out; + i++; + *dst = (s8)0; + } + return i; +err_out: + return -ENOSPC; +} + +/** + * ntfs_mapping_pairs_build - build the mapping pairs array from a runlist + * @vol: ntfs volume (needed for the ntfs version) + * @dst: destination buffer to which to write the mapping pairs array + * @dst_len: size of destination buffer @dst in bytes + * @rl: locked runlist for which to build the mapping pairs array + * @start_vcn: vcn at which to start the mapping pairs array + * @stop_vcn: first vcn outside destination buffer on success or -ENOSPC + * + * Create the mapping pairs array from the locked runlist @rl, starting at vcn + * @start_vcn and save the array in @dst. @dst_len is the size of @dst in + * bytes and it should be at least equal to the value obtained by calling + * ntfs_get_size_for_mapping_pairs(). + * + * If @rl is NULL, just write a single terminator byte to @dst. + * + * On success or -ENOSPC error, if @stop_vcn is not NULL, *@stop_vcn is set to + * the first vcn outside the destination buffer. Note that on error, @dst has + * been filled with all the mapping pairs that will fit, thus it can be treated + * as partial success, in that a new attribute extent needs to be created or + * the next extent has to be used and the mapping pairs build has to be + * continued with @start_vcn set to *@stop_vcn. + * + * Return 0 on success and -errno on error. The following error codes are + * defined: + * -EINVAL - Run list contains unmapped elements. Make sure to only pass + * fully mapped runlists to this function. + * -EIO - The runlist is corrupt. + * -ENOSPC - The destination buffer is too small. + * + * Locking: @rl must be locked on entry (either for reading or writing), it + * remains locked throughout, and is left locked upon return. + */ +int ntfs_mapping_pairs_build(const ntfs_volume *vol, s8 *dst, + const int dst_len, const runlist_element *rl, + const VCN start_vcn, VCN *const stop_vcn) +{ + LCN prev_lcn; + s8 *dst_max, *dst_next; + int err = -ENOSPC; + s8 len_len, lcn_len; + + BUG_ON(start_vcn < 0); + BUG_ON(dst_len < 1); + if (!rl) { + BUG_ON(start_vcn); + if (stop_vcn) + *stop_vcn = 0; + /* Terminator byte. */ + *dst = 0; + return 0; + } + /* Skip to runlist element containing @start_vcn. */ + while (rl->length && start_vcn >= rl[1].vcn) + rl++; + if ((!rl->length && start_vcn > rl->vcn) || start_vcn < rl->vcn) + return -EINVAL; + /* + * @dst_max is used for bounds checking in + * ntfs_write_significant_bytes(). + */ + dst_max = dst + dst_len - 1; + prev_lcn = 0; + /* Do the first partial run if present. */ + if (start_vcn > rl->vcn) { + s64 delta; + + /* We know rl->length != 0 already. */ + if (rl->length < 0 || rl->lcn < LCN_HOLE) + goto err_out; + delta = start_vcn - rl->vcn; + /* Write length. */ + len_len = ntfs_write_significant_bytes(dst + 1, dst_max, + rl->length - delta); + if (len_len < 0) + goto size_err; + /* + * If the logical cluster number (lcn) denotes a hole and we + * are on NTFS 3.0+, we don't store it at all, i.e. we need + * zero space. On earlier NTFS versions we just write the lcn + * change. FIXME: Do we need to write the lcn change or just + * the lcn in that case? Not sure as I have never seen this + * case on NT4. - We assume that we just need to write the lcn + * change until someone tells us otherwise... (AIA) + */ + if (rl->lcn >= 0 || vol->major_ver < 3) { + prev_lcn = rl->lcn; + if (rl->lcn >= 0) + prev_lcn += delta; + /* Write change in lcn. */ + lcn_len = ntfs_write_significant_bytes(dst + 1 + + len_len, dst_max, prev_lcn); + if (lcn_len < 0) + goto size_err; + } else + lcn_len = 0; + dst_next = dst + len_len + lcn_len + 1; + if (dst_next > dst_max) + goto size_err; + /* Update header byte. */ + *dst = lcn_len << 4 | len_len; + /* Position at next mapping pairs array element. */ + dst = dst_next; + /* Go to next runlist element. */ + rl++; + } + /* Do the full runs. */ + for (; rl->length; rl++) { + if (rl->length < 0 || rl->lcn < LCN_HOLE) + goto err_out; + /* Write length. */ + len_len = ntfs_write_significant_bytes(dst + 1, dst_max, + rl->length); + if (len_len < 0) + goto size_err; + /* + * If the logical cluster number (lcn) denotes a hole and we + * are on NTFS 3.0+, we don't store it at all, i.e. we need + * zero space. On earlier NTFS versions we just write the lcn + * change. FIXME: Do we need to write the lcn change or just + * the lcn in that case? Not sure as I have never seen this + * case on NT4. - We assume that we just need to write the lcn + * change until someone tells us otherwise... (AIA) + */ + if (rl->lcn >= 0 || vol->major_ver < 3) { + /* Write change in lcn. */ + lcn_len = ntfs_write_significant_bytes(dst + 1 + + len_len, dst_max, rl->lcn - prev_lcn); + if (lcn_len < 0) + goto size_err; + prev_lcn = rl->lcn; + } else + lcn_len = 0; + dst_next = dst + len_len + lcn_len + 1; + if (dst_next > dst_max) + goto size_err; + /* Update header byte. */ + *dst = lcn_len << 4 | len_len; + /* Position at next mapping pairs array element. */ + dst = dst_next; + } + /* Success. */ + err = 0; +size_err: + /* Set stop vcn. */ + if (stop_vcn) + *stop_vcn = rl->vcn; + /* Add terminator byte. */ + *dst = 0; + return err; +err_out: + if (rl->lcn == LCN_RL_NOT_MAPPED) + err = -EINVAL; + else + err = -EIO; + return err; +} + +/** + * ntfs_rl_truncate_nolock - truncate a runlist starting at a specified vcn + * @runlist: runlist to truncate + * @new_length: the new length of the runlist in VCNs + * + * Truncate the runlist described by @runlist as well as the memory buffer + * 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. + * + * 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. + * + * Return 0 on success and -errno on error. + * + * Locking: The caller must hold @runlist->lock for writing. + */ +int ntfs_rl_truncate_nolock(const ntfs_volume *vol, runlist *const runlist, + const s64 new_length) +{ + runlist_element *rl; + int old_size; + + ntfs_debug("Entering for new_length 0x%llx.", (long long)new_length); + BUG_ON(!runlist); + BUG_ON(new_length < 0); + rl = runlist->rl; + if (unlikely(!rl)) { + /* + * Create a runlist consisting of a sparse runlist element of + * length @new_length followed by a terminator runlist element. + */ + rl = ntfs_malloc_nofs(PAGE_SIZE); + if (unlikely(!rl)) { + ntfs_error(vol->sb, "Not enough memory to allocate " + "runlist element buffer."); + return -ENOMEM; + } + runlist->rl = rl; + rl[1].length = rl->vcn = 0; + rl->lcn = LCN_HOLE; + rl[1].vcn = rl->length = new_length; + rl[1].lcn = LCN_ENOENT; + return 0; + } + BUG_ON(new_length < rl->vcn); + /* Find @new_length in the runlist. */ + while (likely(rl->length && new_length >= rl[1].vcn)) + rl++; + /* + * If not at the end of the runlist we need to shrink it. + * If at the end of the runlist we need to expand it. + */ + if (rl->length) { + runlist_element *trl; + BOOL is_end; + + ntfs_debug("Shrinking runlist."); + /* Determine the runlist size. */ + trl = rl + 1; + while (likely(trl->length)) + trl++; + old_size = trl - runlist->rl + 1; + /* Truncate the run. */ + rl->length = new_length - rl->vcn; + /* + * If a run was partially truncated, make the following runlist + * element a terminator. + */ + is_end = FALSE; + if (rl->length) { + rl++; + if (!rl->length) + is_end = TRUE; + rl->vcn = new_length; + rl->length = 0; + } + rl->lcn = LCN_ENOENT; + /* Reallocate memory if necessary. */ + if (!is_end) { + int new_size = rl - runlist->rl + 1; + rl = ntfs_rl_realloc(runlist->rl, old_size, new_size); + 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; + } + } else if (likely(/* !rl->length && */ new_length > rl->vcn)) { + ntfs_debug("Expanding runlist."); + /* + * If there is a previous runlist element and it is a sparse + * one, extend it. Otherwise need to add a new, sparse runlist + * element. + */ + if ((rl > runlist->rl) && ((rl - 1)->lcn == LCN_HOLE)) + (rl - 1)->length = new_length - (rl - 1)->vcn; + else { + /* Determine the runlist size. */ + old_size = rl - runlist->rl + 1; + /* Reallocate memory if necessary. */ + rl = ntfs_rl_realloc(runlist->rl, old_size, + old_size + 1); + if (IS_ERR(rl)) { + ntfs_error(vol->sb, "Failed to expand runlist " + "buffer, aborting."); + return PTR_ERR(rl); + } + runlist->rl = rl; + /* + * Set @rl to the same runlist element in the new + * runlist as before in the old runlist. + */ + rl += old_size - 1; + /* Add a new, sparse runlist element. */ + rl->lcn = LCN_HOLE; + rl->length = new_length - rl->vcn; + /* Add a new terminator runlist element. */ + rl++; + rl->length = 0; + } + rl->vcn = new_length; + rl->lcn = LCN_ENOENT; + } else /* if (unlikely(!rl->length && new_length == rl->vcn)) */ { + /* Runlist already has same size as requested. */ + rl->lcn = LCN_ENOENT; + } + ntfs_debug("Done."); + return 0; +} |
