cregit-Linux how code gets into the kernel

Release 4.10 fs/ubifs/commit.c

Directory: fs/ubifs
/*
 * This file is part of UBIFS.
 *
 * Copyright (C) 2006-2008 Nokia Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * This program 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; if not, write to the Free Software Foundation, Inc., 51
 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * Authors: Adrian Hunter
 *          Artem Bityutskiy (Битюцкий Артём)
 */

/*
 * This file implements functions that manage the running of the commit process.
 * Each affected module has its own functions to accomplish their part in the
 * commit and those functions are called here.
 *
 * The commit is the process whereby all updates to the index and LEB properties
 * are written out together and the journal becomes empty. This keeps the
 * file system consistent - at all times the state can be recreated by reading
 * the index and LEB properties and then replaying the journal.
 *
 * The commit is split into two parts named "commit start" and "commit end".
 * During commit start, the commit process has exclusive access to the journal
 * by holding the commit semaphore down for writing. As few I/O operations as
 * possible are performed during commit start, instead the nodes that are to be
 * written are merely identified. During commit end, the commit semaphore is no
 * longer held and the journal is again in operation, allowing users to continue
 * to use the file system while the bulk of the commit I/O is performed. The
 * purpose of this two-step approach is to prevent the commit from causing any
 * latency blips. Note that in any case, the commit does not prevent lookups
 * (as permitted by the TNC mutex), or access to VFS data structures e.g. page
 * cache.
 */

#include <linux/freezer.h>
#include <linux/kthread.h>
#include <linux/slab.h>
#include "ubifs.h"

/*
 * nothing_to_commit - check if there is nothing to commit.
 * @c: UBIFS file-system description object
 *
 * This is a helper function which checks if there is anything to commit. It is
 * used as an optimization to avoid starting the commit if it is not really
 * necessary. Indeed, the commit operation always assumes flash I/O (e.g.,
 * writing the commit start node to the log), and it is better to avoid doing
 * this unnecessarily. E.g., 'ubifs_sync_fs()' runs the commit, but if there is
 * nothing to commit, it is more optimal to avoid any flash I/O.
 *
 * This function has to be called with @c->commit_sem locked for writing -
 * this function does not take LPT/TNC locks because the @c->commit_sem
 * guarantees that we have exclusive access to the TNC and LPT data structures.
 *
 * This function returns %1 if there is nothing to commit and %0 otherwise.
 */

static int nothing_to_commit(struct ubifs_info *c) { /* * During mounting or remounting from R/O mode to R/W mode we may * commit for various recovery-related reasons. */ if (c->mounting || c->remounting_rw) return 0; /* * If the root TNC node is dirty, we definitely have something to * commit. */ if (c->zroot.znode && ubifs_zn_dirty(c->zroot.znode)) return 0; /* * Even though the TNC is clean, the LPT tree may have dirty nodes. For * example, this may happen if the budgeting subsystem invoked GC to * make some free space, and the GC found an LEB with only dirty and * free space. In this case GC would just change the lprops of this * LEB (by turning all space into free space) and unmap it. */ if (c->nroot && test_bit(DIRTY_CNODE, &c->nroot->flags)) return 0; ubifs_assert(atomic_long_read(&c->dirty_zn_cnt) == 0); ubifs_assert(c->dirty_pn_cnt == 0); ubifs_assert(c->dirty_nn_cnt == 0); return 1; }

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artem bityutskiyartem bityutskiy102100.00%2100.00%
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/** * do_commit - commit the journal. * @c: UBIFS file-system description object * * This function implements UBIFS commit. It has to be called with commit lock * locked. Returns zero in case of success and a negative error code in case of * failure. */
static int do_commit(struct ubifs_info *c) { int err, new_ltail_lnum, old_ltail_lnum, i; struct ubifs_zbranch zroot; struct ubifs_lp_stats lst; dbg_cmt("start"); ubifs_assert(!c->ro_media && !c->ro_mount); if (c->ro_error) { err = -EROFS; goto out_up; } if (nothing_to_commit(c)) { up_write(&c->commit_sem); err = 0; goto out_cancel; } /* Sync all write buffers (necessary for recovery) */ for (i = 0; i < c->jhead_cnt; i++) { err = ubifs_wbuf_sync(&c->jheads[i].wbuf); if (err) goto out_up; } c->cmt_no += 1; err = ubifs_gc_start_commit(c); if (err) goto out_up; err = dbg_check_lprops(c); if (err) goto out_up; err = ubifs_log_start_commit(c, &new_ltail_lnum); if (err) goto out_up; err = ubifs_tnc_start_commit(c, &zroot); if (err) goto out_up; err = ubifs_lpt_start_commit(c); if (err) goto out_up; err = ubifs_orphan_start_commit(c); if (err) goto out_up; ubifs_get_lp_stats(c, &lst); up_write(&c->commit_sem); err = ubifs_tnc_end_commit(c); if (err) goto out; err = ubifs_lpt_end_commit(c); if (err) goto out; err = ubifs_orphan_end_commit(c); if (err) goto out; err = dbg_check_old_index(c, &zroot); if (err) goto out; c->mst_node->cmt_no = cpu_to_le64(c->cmt_no); c->mst_node->log_lnum = cpu_to_le32(new_ltail_lnum); c->mst_node->root_lnum = cpu_to_le32(zroot.lnum); c->mst_node->root_offs = cpu_to_le32(zroot.offs); c->mst_node->root_len = cpu_to_le32(zroot.len); c->mst_node->ihead_lnum = cpu_to_le32(c->ihead_lnum); c->mst_node->ihead_offs = cpu_to_le32(c->ihead_offs); c->mst_node->index_size = cpu_to_le64(c->bi.old_idx_sz); c->mst_node->lpt_lnum = cpu_to_le32(c->lpt_lnum); c->mst_node->lpt_offs = cpu_to_le32(c->lpt_offs); c->mst_node->nhead_lnum = cpu_to_le32(c->nhead_lnum); c->mst_node->nhead_offs = cpu_to_le32(c->nhead_offs); c->mst_node->ltab_lnum = cpu_to_le32(c->ltab_lnum); c->mst_node->ltab_offs = cpu_to_le32(c->ltab_offs); c->mst_node->lsave_lnum = cpu_to_le32(c->lsave_lnum); c->mst_node->lsave_offs = cpu_to_le32(c->lsave_offs); c->mst_node->lscan_lnum = cpu_to_le32(c->lscan_lnum); c->mst_node->empty_lebs = cpu_to_le32(lst.empty_lebs); c->mst_node->idx_lebs = cpu_to_le32(lst.idx_lebs); c->mst_node->total_free = cpu_to_le64(lst.total_free); c->mst_node->total_dirty = cpu_to_le64(lst.total_dirty); c->mst_node->total_used = cpu_to_le64(lst.total_used); c->mst_node->total_dead = cpu_to_le64(lst.total_dead); c->mst_node->total_dark = cpu_to_le64(lst.total_dark); if (c->no_orphs) c->mst_node->flags |= cpu_to_le32(UBIFS_MST_NO_ORPHS); else c->mst_node->flags &= ~cpu_to_le32(UBIFS_MST_NO_ORPHS); old_ltail_lnum = c->ltail_lnum; err = ubifs_log_end_commit(c, new_ltail_lnum); if (err) goto out; err = ubifs_log_post_commit(c, old_ltail_lnum); if (err) goto out; err = ubifs_gc_end_commit(c); if (err) goto out; err = ubifs_lpt_post_commit(c); if (err) goto out; out_cancel: spin_lock(&c->cs_lock); c->cmt_state = COMMIT_RESTING; wake_up(&c->cmt_wq); dbg_cmt("commit end"); spin_unlock(&c->cs_lock); return 0; out_up: up_write(&c->commit_sem); out: ubifs_err(c, "commit failed, error %d", err); spin_lock(&c->cs_lock); c->cmt_state = COMMIT_BROKEN; wake_up(&c->cmt_wq); spin_unlock(&c->cs_lock); ubifs_ro_mode(c, err); return err; }

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artem bityutskiyartem bityutskiy80499.75%787.50%
sheng yongsheng yong20.25%112.50%
Total806100.00%8100.00%

/** * run_bg_commit - run background commit if it is needed. * @c: UBIFS file-system description object * * This function runs background commit if it is needed. Returns zero in case * of success and a negative error code in case of failure. */
static int run_bg_commit(struct ubifs_info *c) { spin_lock(&c->cs_lock); /* * Run background commit only if background commit was requested or if * commit is required. */ if (c->cmt_state != COMMIT_BACKGROUND && c->cmt_state != COMMIT_REQUIRED) goto out; spin_unlock(&c->cs_lock); down_write(&c->commit_sem); spin_lock(&c->cs_lock); if (c->cmt_state == COMMIT_REQUIRED) c->cmt_state = COMMIT_RUNNING_REQUIRED; else if (c->cmt_state == COMMIT_BACKGROUND) c->cmt_state = COMMIT_RUNNING_BACKGROUND; else goto out_cmt_unlock; spin_unlock(&c->cs_lock); return do_commit(c); out_cmt_unlock: up_write(&c->commit_sem); out: spin_unlock(&c->cs_lock); return 0; }

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artem bityutskiyartem bityutskiy131100.00%1100.00%
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/** * ubifs_bg_thread - UBIFS background thread function. * @info: points to the file-system description object * * This function implements various file-system background activities: * o when a write-buffer timer expires it synchronizes the appropriate * write-buffer; * o when the journal is about to be full, it starts in-advance commit. * * Note, other stuff like background garbage collection may be added here in * future. */
int ubifs_bg_thread(void *info) { int err; struct ubifs_info *c = info; ubifs_msg(c, "background thread \"%s\" started, PID %d", c->bgt_name, current->pid); set_freezable(); while (1) { if (kthread_should_stop()) break; if (try_to_freeze()) continue; set_current_state(TASK_INTERRUPTIBLE); /* Check if there is something to do */ if (!c->need_bgt) { /* * Nothing prevents us from going sleep now and * be never woken up and block the task which * could wait in 'kthread_stop()' forever. */ if (kthread_should_stop()) break; schedule(); continue; } else __set_current_state(TASK_RUNNING); c->need_bgt = 0; err = ubifs_bg_wbufs_sync(c); if (err) ubifs_ro_mode(c, err); run_bg_commit(c); cond_resched(); } ubifs_msg(c, "background thread \"%s\" stops", c->bgt_name); return 0; }

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artem bityutskiyartem bityutskiy12996.99%266.67%
sheng yongsheng yong43.01%133.33%
Total133100.00%3100.00%

/** * ubifs_commit_required - set commit state to "required". * @c: UBIFS file-system description object * * This function is called if a commit is required but cannot be done from the * calling function, so it is just flagged instead. */
void ubifs_commit_required(struct ubifs_info *c) { spin_lock(&c->cs_lock); switch (c->cmt_state) { case COMMIT_RESTING: case COMMIT_BACKGROUND: dbg_cmt("old: %s, new: %s", dbg_cstate(c->cmt_state), dbg_cstate(COMMIT_REQUIRED)); c->cmt_state = COMMIT_REQUIRED; break; case COMMIT_RUNNING_BACKGROUND: dbg_cmt("old: %s, new: %s", dbg_cstate(c->cmt_state), dbg_cstate(COMMIT_RUNNING_REQUIRED)); c->cmt_state = COMMIT_RUNNING_REQUIRED; break; case COMMIT_REQUIRED: case COMMIT_RUNNING_REQUIRED: case COMMIT_BROKEN: break; } spin_unlock(&c->cs_lock); }

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artem bityutskiyartem bityutskiy101100.00%1100.00%
Total101100.00%1100.00%

/** * ubifs_request_bg_commit - notify the background thread to do a commit. * @c: UBIFS file-system description object * * This function is called if the journal is full enough to make a commit * worthwhile, so background thread is kicked to start it. */
void ubifs_request_bg_commit(struct ubifs_info *c) { spin_lock(&c->cs_lock); if (c->cmt_state == COMMIT_RESTING) { dbg_cmt("old: %s, new: %s", dbg_cstate(c->cmt_state), dbg_cstate(COMMIT_BACKGROUND)); c->cmt_state = COMMIT_BACKGROUND; spin_unlock(&c->cs_lock); ubifs_wake_up_bgt(c); } else spin_unlock(&c->cs_lock); }

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artem bityutskiyartem bityutskiy73100.00%1100.00%
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/** * wait_for_commit - wait for commit. * @c: UBIFS file-system description object * * This function sleeps until the commit operation is no longer running. */
static int wait_for_commit(struct ubifs_info *c) { dbg_cmt("pid %d goes sleep", current->pid); /* * The following sleeps if the condition is false, and will be woken * when the commit ends. It is possible, although very unlikely, that we * will wake up and see the subsequent commit running, rather than the * one we were waiting for, and go back to sleep. However, we will be * woken again, so there is no danger of sleeping forever. */ wait_event(c->cmt_wq, c->cmt_state != COMMIT_RUNNING_BACKGROUND && c->cmt_state != COMMIT_RUNNING_REQUIRED); dbg_cmt("commit finished, pid %d woke up", current->pid); return 0; }

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artem bityutskiyartem bityutskiy52100.00%1100.00%
Total52100.00%1100.00%

/** * ubifs_run_commit - run or wait for commit. * @c: UBIFS file-system description object * * This function runs commit and returns zero in case of success and a negative * error code in case of failure. */
int ubifs_run_commit(struct ubifs_info *c) { int err = 0; spin_lock(&c->cs_lock); if (c->cmt_state == COMMIT_BROKEN) { err = -EROFS; goto out; } if (c->cmt_state == COMMIT_RUNNING_BACKGROUND) /* * We set the commit state to 'running required' to indicate * that we want it to complete as quickly as possible. */ c->cmt_state = COMMIT_RUNNING_REQUIRED; if (c->cmt_state == COMMIT_RUNNING_REQUIRED) { spin_unlock(&c->cs_lock); return wait_for_commit(c); } spin_unlock(&c->cs_lock); /* Ok, the commit is indeed needed */ down_write(&c->commit_sem); spin_lock(&c->cs_lock); /* * Since we unlocked 'c->cs_lock', the state may have changed, so * re-check it. */ if (c->cmt_state == COMMIT_BROKEN) { err = -EROFS; goto out_cmt_unlock; } if (c->cmt_state == COMMIT_RUNNING_BACKGROUND) c->cmt_state = COMMIT_RUNNING_REQUIRED; if (c->cmt_state == COMMIT_RUNNING_REQUIRED) { up_write(&c->commit_sem); spin_unlock(&c->cs_lock); return wait_for_commit(c); } c->cmt_state = COMMIT_RUNNING_REQUIRED; spin_unlock(&c->cs_lock); err = do_commit(c); return err; out_cmt_unlock: up_write(&c->commit_sem); out: spin_unlock(&c->cs_lock); return err; }

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artem bityutskiyartem bityutskiy217100.00%2100.00%
Total217100.00%2100.00%

/** * ubifs_gc_should_commit - determine if it is time for GC to run commit. * @c: UBIFS file-system description object * * This function is called by garbage collection to determine if commit should * be run. If commit state is @COMMIT_BACKGROUND, which means that the journal * is full enough to start commit, this function returns true. It is not * absolutely necessary to commit yet, but it feels like this should be better * then to keep doing GC. This function returns %1 if GC has to initiate commit * and %0 if not. */
int ubifs_gc_should_commit(struct ubifs_info *c) { int ret = 0; spin_lock(&c->cs_lock); if (c->cmt_state == COMMIT_BACKGROUND) { dbg_cmt("commit required now"); c->cmt_state = COMMIT_REQUIRED; } else dbg_cmt("commit not requested"); if (c->cmt_state == COMMIT_REQUIRED) ret = 1; spin_unlock(&c->cs_lock); return ret; }

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artem bityutskiyartem bityutskiy73100.00%1100.00%
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/* * Everything below is related to debugging. */ /** * struct idx_node - hold index nodes during index tree traversal. * @list: list * @iip: index in parent (slot number of this indexing node in the parent * indexing node) * @upper_key: all keys in this indexing node have to be less or equivalent to * this key * @idx: index node (8-byte aligned because all node structures must be 8-byte * aligned) */ struct idx_node { struct list_head list; int iip; union ubifs_key upper_key; struct ubifs_idx_node idx __aligned(8); }; /** * dbg_old_index_check_init - get information for the next old index check. * @c: UBIFS file-system description object * @zroot: root of the index * * This function records information about the index that will be needed for the * next old index check i.e. 'dbg_check_old_index()'. * * This function returns %0 on success and a negative error code on failure. */
int dbg_old_index_check_init(struct ubifs_info *c, struct ubifs_zbranch *zroot) { struct ubifs_idx_node *idx; int lnum, offs, len, err = 0; struct ubifs_debug_info *d = c->dbg; d->old_zroot = *zroot; lnum = d->old_zroot.lnum; offs = d->old_zroot.offs; len = d->old_zroot.len; idx = kmalloc(c->max_idx_node_sz, GFP_NOFS); if (!idx) return -ENOMEM; err = ubifs_read_node(c, idx, UBIFS_IDX_NODE, len, lnum, offs); if (err) goto out; d->old_zroot_level = le16_to_cpu(idx->level); d->old_zroot_sqnum = le64_to_cpu(idx->ch.sqnum); out: kfree(idx); return err; }

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artem bityutskiyartem bityutskiy149100.00%2100.00%
Total149100.00%2100.00%

/** * dbg_check_old_index - check the old copy of the index. * @c: UBIFS file-system description object * @zroot: root of the new index * * In order to be able to recover from an unclean unmount, a complete copy of * the index must exist on flash. This is the "old" index. The commit process * must write the "new" index to flash without overwriting or destroying any * part of the old index. This function is run at commit end in order to check * that the old index does indeed exist completely intact. * * This function returns %0 on success and a negative error code on failure. */
int dbg_check_old_index(struct ubifs_info *c, struct ubifs_zbranch *zroot) { int lnum, offs, len, err = 0, uninitialized_var(last_level), child_cnt; int first = 1, iip; struct ubifs_debug_info *d = c->dbg; union ubifs_key uninitialized_var(lower_key), upper_key, l_key, u_key; unsigned long long uninitialized_var(last_sqnum); struct ubifs_idx_node *idx; struct list_head list; struct idx_node *i; size_t sz; if (!dbg_is_chk_index(c)) return 0; INIT_LIST_HEAD(&list); sz = sizeof(struct idx_node) + ubifs_idx_node_sz(c, c->fanout) - UBIFS_IDX_NODE_SZ; /* Start at the old zroot */ lnum = d->old_zroot.lnum; offs = d->old_zroot.offs; len = d->old_zroot.len; iip = 0; /* * Traverse the index tree preorder depth-first i.e. do a node and then * its subtrees from left to right. */ while (1) { struct ubifs_branch *br; /* Get the next index node */ i = kmalloc(sz, GFP_NOFS); if (!i) { err = -ENOMEM; goto out_free; } i->iip = iip; /* Keep the index nodes on our path in a linked list */ list_add_tail(&i->list, &list); /* Read the index node */ idx = &i->idx; err = ubifs_read_node(c, idx, UBIFS_IDX_NODE, len, lnum, offs); if (err) goto out_free; /* Validate index node */ child_cnt = le16_to_cpu(idx->child_cnt); if (child_cnt < 1 || child_cnt > c->fanout) { err = 1; goto out_dump; } if (first) { first = 0; /* Check root level and sqnum */ if (le16_to_cpu(idx->level) != d->old_zroot_level) { err = 2; goto out_dump; } if (le64_to_cpu(idx->ch.sqnum) != d->old_zroot_sqnum) { err = 3; goto out_dump; } /* Set last values as though root had a parent */ last_level = le16_to_cpu(idx->level) + 1; last_sqnum = le64_to_cpu(idx->ch.sqnum) + 1; key_read(c, ubifs_idx_key(c, idx), &lower_key); highest_ino_key(c, &upper_key, INUM_WATERMARK); } key_copy(c, &upper_key, &i->upper_key); if (le16_to_cpu(idx->level) != last_level - 1) { err = 3; goto out_dump; } /* * The index is always written bottom up hence a child's sqnum * is always less than the parents. */ if (le64_to_cpu(idx->ch.sqnum) >= last_sqnum) { err = 4; goto out_dump; } /* Check key range */ key_read(c, ubifs_idx_key(c, idx), &l_key); br = ubifs_idx_branch(c, idx, child_cnt - 1); key_read(c, &br->key, &u_key); if (keys_cmp(c, &lower_key, &l_key) > 0) { err = 5; goto out_dump; } if (keys_cmp(c, &upper_key, &u_key) < 0) { err = 6; goto out_dump; } if (keys_cmp(c, &upper_key, &u_key) == 0) if (!is_hash_key(c, &u_key)) { err = 7; goto out_dump; } /* Go to next index node */ if (le16_to_cpu(idx->level) == 0) { /* At the bottom, so go up until can go right */ while (1) { /* Drop the bottom of the list */ list_del(&i->list); kfree(i); /* No more list means we are done */ if (list_empty(&list)) goto out; /* Look at the new bottom */ i = list_entry(list.prev, struct idx_node, list); idx = &i->idx; /* Can we go right */ if (iip + 1 < le16_to_cpu(idx->child_cnt)) { iip = iip + 1; break; } else /* Nope, so go up again */ iip = i->iip; } } else /* Go down left */ iip = 0; /* * We have the parent in 'idx' and now we set up for reading the * child pointed to by slot 'iip'. */ last_level = le16_to_cpu(idx->level); last_sqnum = le64_to_cpu(idx->ch.sqnum); br = ubifs_idx_branch(c, idx, iip); lnum = le32_to_cpu(br->lnum); offs = le32_to_cpu(br->offs); len = le32_to_cpu(br->len); key_read(c, &br->key, &lower_key); if (iip + 1 < le16_to_cpu(idx->child_cnt)) { br = ubifs_idx_branch(c, idx, iip + 1); key_read(c, &br->key, &upper_key); } else key_copy(c, &i->upper_key, &upper_key); } out: err = dbg_old_index_check_init(c, zroot); if (err) goto out_free; return 0; out_dump: ubifs_err(c, "dumping index node (iip=%d)", i->iip); ubifs_dump_node(c, idx); list_del(&i->list); kfree(i); if (!list_empty(&list)) { i = list_entry(list.prev, struct idx_node, list); ubifs_err(c, "dumping parent index node"); ubifs_dump_node(c, &i->idx); } out_free: while (!list_empty(&list)) { i = list_entry(list.next, struct idx_node, list); list_del(&i->list); kfree(i); } ubifs_err(c, "failed, error %d", err); if (err > 0) err = -EINVAL; return err; }

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artem bityutskiyartem bityutskiy94399.05%777.78%
sheng yongsheng yong60.63%111.11%
subrata modaksubrata modak30.32%111.11%
Total952100.00%9100.00%


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artem bityutskiyartem bityutskiy282299.37%1885.71%
sheng yongsheng yong120.42%14.76%
tejun heotejun heo30.11%14.76%
subrata modaksubrata modak30.11%14.76%
Total2840100.00%21100.00%
Directory: fs/ubifs
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