From patchwork Mon Jun 27 18:02:22 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Josef Bacik X-Patchwork-Id: 921922 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter2.kernel.org (8.14.4/8.14.4) with ESMTP id p5RI5U8U015550 for ; Mon, 27 Jun 2011 18:05:30 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753200Ab1F0SCz (ORCPT ); Mon, 27 Jun 2011 14:02:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:22266 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753075Ab1F0SCc (ORCPT ); Mon, 27 Jun 2011 14:02:32 -0400 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id p5RI2W71012091 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Mon, 27 Jun 2011 14:02:32 -0400 Received: from localhost.localdomain.com (vpn-8-183.rdu.redhat.com [10.11.8.183]) by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id p5RI2RPM014189; Mon, 27 Jun 2011 14:02:30 -0400 From: Josef Bacik To: linux-fsdevel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, viro@ZenIV.linux.org.uk Subject: [PATCH 2/4] Btrfs: implement our own ->llseek Date: Mon, 27 Jun 2011 14:02:22 -0400 Message-Id: <1309197745-14107-2-git-send-email-josef@redhat.com> In-Reply-To: <1309197745-14107-1-git-send-email-josef@redhat.com> References: <1309197745-14107-1-git-send-email-josef@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.12 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.6 (demeter2.kernel.org [140.211.167.43]); Mon, 27 Jun 2011 18:05:30 +0000 (UTC) In order to handle SEEK_HOLE/SEEK_DATA we need to implement our own llseek. Basically for the normal SEEK_*'s we will just defer to the generic helper, and for SEEK_HOLE/SEEK_DATA we will use our fiemap helper to figure out the nearest hole or data. Currently this helper doesn't check for delalloc bytes for prealloc space, so for now treat prealloc as data until that is fixed. Thanks, Signed-off-by: Josef Bacik --- fs/btrfs/ctree.h | 3 + fs/btrfs/file.c | 148 +++++++++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 150 insertions(+), 1 deletions(-) diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 3006287..8040f4b 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -2506,6 +2506,9 @@ int btrfs_csum_truncate(struct btrfs_trans_handle *trans, int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end, struct list_head *list, int search_commit); /* inode.c */ +struct extent_map *btrfs_get_extent_fiemap(struct inode *inode, struct page *page, + size_t pg_offset, u64 start, u64 len, + int create); /* RHEL and EL kernels have a patch that renames PG_checked to FsMisc */ #if defined(ClearPageFsMisc) && !defined(ClearPageChecked) diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index fa4ef18..bd4d061 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1664,8 +1664,154 @@ out: return ret; } +static int find_desired_extent(struct inode *inode, loff_t *offset, int origin) +{ + struct btrfs_root *root = BTRFS_I(inode)->root; + struct extent_map *em; + struct extent_state *cached_state = NULL; + u64 lockstart = *offset; + u64 lockend = i_size_read(inode); + u64 start = *offset; + u64 orig_start = *offset; + u64 len = i_size_read(inode); + u64 last_end = 0; + int ret = 0; + + lockend = max_t(u64, root->sectorsize, lockend); + if (lockend <= lockstart) + lockend = lockstart + root->sectorsize; + + len = lockend - lockstart + 1; + + len = max_t(u64, len, root->sectorsize); + if (inode->i_size == 0) + return -ENXIO; + + lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend, 0, + &cached_state, GFP_NOFS); + + /* + * Delalloc is such a pain. If we have a hole and we have pending + * delalloc for a portion of the hole we will get back a hole that + * exists for the entire range since it hasn't been actually written + * yet. So to take care of this case we need to look for an extent just + * before the position we want in case there is outstanding delalloc + * going on here. + */ + if (origin == SEEK_HOLE && start != 0) { + if (start <= root->sectorsize) + em = btrfs_get_extent_fiemap(inode, NULL, 0, 0, + root->sectorsize, 0); + else + em = btrfs_get_extent_fiemap(inode, NULL, 0, + start - root->sectorsize, + root->sectorsize, 0); + if (IS_ERR(em)) { + ret = -ENXIO; + goto out; + } + last_end = em->start + em->len; + if (em->block_start == EXTENT_MAP_DELALLOC) + last_end = min_t(u64, last_end, inode->i_size); + free_extent_map(em); + } + + while (1) { + em = btrfs_get_extent_fiemap(inode, NULL, 0, start, len, 0); + if (IS_ERR(em)) { + ret = -ENXIO; + break; + } + + if (em->block_start == EXTENT_MAP_HOLE) { + if (test_bit(EXTENT_FLAG_VACANCY, &em->flags)) { + if (last_end <= orig_start) { + free_extent_map(em); + ret = -ENXIO; + break; + } + } + + if (origin == SEEK_HOLE) { + *offset = start; + free_extent_map(em); + break; + } + } else { + if (origin == SEEK_DATA) { + if (em->block_start == EXTENT_MAP_DELALLOC) { + if (start >= inode->i_size) { + free_extent_map(em); + ret = -ENXIO; + break; + } + } + + *offset = start; + free_extent_map(em); + break; + } + } + + start = em->start + em->len; + last_end = em->start + em->len; + + if (em->block_start == EXTENT_MAP_DELALLOC) + last_end = min_t(u64, last_end, inode->i_size); + + if (test_bit(EXTENT_FLAG_VACANCY, &em->flags)) { + free_extent_map(em); + ret = -ENXIO; + break; + } + free_extent_map(em); + cond_resched(); + } + if (!ret) + *offset = min(*offset, inode->i_size); +out: + unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend, + &cached_state, GFP_NOFS); + return ret; +} + +static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int origin) +{ + struct inode *inode = file->f_mapping->host; + int ret; + + mutex_lock(&inode->i_mutex); + switch (origin) { + case SEEK_END: + case SEEK_CUR: + offset = generic_file_llseek_unlocked(file, offset, origin); + goto out; + case SEEK_DATA: + case SEEK_HOLE: + ret = find_desired_extent(inode, &offset, origin); + if (ret) { + mutex_unlock(&inode->i_mutex); + return ret; + } + } + + if (offset < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET)) + return -EINVAL; + if (offset > inode->i_sb->s_maxbytes) + return -EINVAL; + + /* Special lock needed here? */ + if (offset != file->f_pos) { + file->f_pos = offset; + file->f_version = 0; + } +out: + mutex_unlock(&inode->i_mutex); + return offset; +} + const struct file_operations btrfs_file_operations = { - .llseek = generic_file_llseek, + .llseek = btrfs_file_llseek, .read = do_sync_read, .write = do_sync_write, .aio_read = generic_file_aio_read,