diff options
Diffstat (limited to 'fs/ntfs/attrib.c')
| -rw-r--r-- | fs/ntfs/attrib.c | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c index fa464fce2261..1610f1cd2862 100644 --- a/fs/ntfs/attrib.c +++ b/fs/ntfs/attrib.c @@ -106,6 +106,93 @@ int ntfs_map_runlist(ntfs_inode *ni, VCN vcn) } /** + * 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 |