X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=fs%2Fubifs%2Fbudget.c;h=076ca50e99336fad10e256ddc3d103ae93fd527a;hb=f13771187b9423b824f32518319f6da85d819003;hp=7851480a6cea97376eb576ead6944d05301cc1be;hpb=4b5f2762ec914c9dfd0e9d2377c0574f2ee9a8f9;p=safe%2Fjmp%2Flinux-2.6 diff --git a/fs/ubifs/budget.c b/fs/ubifs/budget.c index 7851480..076ca50 100644 --- a/fs/ubifs/budget.c +++ b/fs/ubifs/budget.c @@ -32,18 +32,15 @@ #include "ubifs.h" #include -#include +#include /* * When pessimistic budget calculations say that there is no enough space, * UBIFS starts writing back dirty inodes and pages, doing garbage collection, - * or committing. The below constants define maximum number of times UBIFS + * or committing. The below constant defines maximum number of times UBIFS * repeats the operations. */ -#define MAX_SHRINK_RETRIES 8 -#define MAX_GC_RETRIES 4 -#define MAX_CMT_RETRIES 2 -#define MAX_NOSPC_RETRIES 1 +#define MAX_MKSPC_RETRIES 3 /* * The below constant defines amount of dirty pages which should be written @@ -52,73 +49,22 @@ #define NR_TO_WRITE 16 /** - * struct retries_info - information about re-tries while making free space. - * @prev_liability: previous liability - * @shrink_cnt: how many times the liability was shrinked - * @shrink_retries: count of liability shrink re-tries (increased when - * liability does not shrink) - * @try_gc: GC should be tried first - * @gc_retries: how many times GC was run - * @cmt_retries: how many times commit has been done - * @nospc_retries: how many times GC returned %-ENOSPC - * - * Since we consider budgeting to be the fast-path, and this structure has to - * be allocated on stack and zeroed out, we make it smaller using bit-fields. - */ -struct retries_info { - long long prev_liability; - unsigned int shrink_cnt; - unsigned int shrink_retries:5; - unsigned int try_gc:1; - unsigned int gc_retries:4; - unsigned int cmt_retries:3; - unsigned int nospc_retries:1; -}; - -/** * shrink_liability - write-back some dirty pages/inodes. * @c: UBIFS file-system description object * @nr_to_write: how many dirty pages to write-back * * This function shrinks UBIFS liability by means of writing back some amount - * of dirty inodes and their pages. Returns the amount of pages which were - * written back. The returned value does not include dirty inodes which were - * synchronized. + * of dirty inodes and their pages. * * Note, this function synchronizes even VFS inodes which are locked * (@i_mutex) by the caller of the budgeting function, because write-back does * not touch @i_mutex. */ -static int shrink_liability(struct ubifs_info *c, int nr_to_write) +static void shrink_liability(struct ubifs_info *c, int nr_to_write) { - int nr_written; - struct writeback_control wbc = { - .sync_mode = WB_SYNC_NONE, - .range_end = LLONG_MAX, - .nr_to_write = nr_to_write, - }; - - generic_sync_sb_inodes(c->vfs_sb, &wbc); - nr_written = nr_to_write - wbc.nr_to_write; - - if (!nr_written) { - /* - * Re-try again but wait on pages/inodes which are being - * written-back concurrently (e.g., by pdflush). - */ - memset(&wbc, 0, sizeof(struct writeback_control)); - wbc.sync_mode = WB_SYNC_ALL; - wbc.range_end = LLONG_MAX; - wbc.nr_to_write = nr_to_write; - generic_sync_sb_inodes(c->vfs_sb, &wbc); - nr_written = nr_to_write - wbc.nr_to_write; - } - - dbg_budg("%d pages were written back", nr_written); - return nr_written; + writeback_inodes_sb(c->vfs_sb); } - /** * run_gc - run garbage collector. * @c: UBIFS file-system description object @@ -147,13 +93,29 @@ static int run_gc(struct ubifs_info *c) } /** + * get_liability - calculate current liability. + * @c: UBIFS file-system description object + * + * This function calculates and returns current UBIFS liability, i.e. the + * amount of bytes UBIFS has "promised" to write to the media. + */ +static long long get_liability(struct ubifs_info *c) +{ + long long liab; + + spin_lock(&c->space_lock); + liab = c->budg_idx_growth + c->budg_data_growth + c->budg_dd_growth; + spin_unlock(&c->space_lock); + return liab; +} + +/** * make_free_space - make more free space on the file-system. * @c: UBIFS file-system description object - * @ri: information about previous invocations of this function * * This function is called when an operation cannot be budgeted because there * is supposedly no free space. But in most cases there is some free space: - * o budgeting is pessimistic, so it always budgets more then it is actually + * o budgeting is pessimistic, so it always budgets more than it is actually * needed, so shrinking the liability is one way to make free space - the * cached data will take less space then it was budgeted for; * o GC may turn some dark space into free space (budgeting treats dark space @@ -165,129 +127,74 @@ static int run_gc(struct ubifs_info *c) * Returns %-ENOSPC if it couldn't do more free space, and other negative error * codes on failures. */ -static int make_free_space(struct ubifs_info *c, struct retries_info *ri) +static int make_free_space(struct ubifs_info *c) { - int err; - - /* - * If we have some dirty pages and inodes (liability), try to write - * them back unless this was tried too many times without effect - * already. - */ - if (ri->shrink_retries < MAX_SHRINK_RETRIES && !ri->try_gc) { - long long liability; - - spin_lock(&c->space_lock); - liability = c->budg_idx_growth + c->budg_data_growth + - c->budg_dd_growth; - spin_unlock(&c->space_lock); - - if (ri->prev_liability >= liability) { - /* Liability does not shrink, next time try GC then */ - ri->shrink_retries += 1; - if (ri->gc_retries < MAX_GC_RETRIES) - ri->try_gc = 1; - dbg_budg("liability did not shrink: retries %d of %d", - ri->shrink_retries, MAX_SHRINK_RETRIES); - } + int err, retries = 0; + long long liab1, liab2; - dbg_budg("force write-back (count %d)", ri->shrink_cnt); - shrink_liability(c, NR_TO_WRITE + ri->shrink_cnt); + do { + liab1 = get_liability(c); + /* + * We probably have some dirty pages or inodes (liability), try + * to write them back. + */ + dbg_budg("liability %lld, run write-back", liab1); + shrink_liability(c, NR_TO_WRITE); - ri->prev_liability = liability; - ri->shrink_cnt += 1; - return -EAGAIN; - } + liab2 = get_liability(c); + if (liab2 < liab1) + return -EAGAIN; - /* - * Try to run garbage collector unless it was already tried too many - * times. - */ - if (ri->gc_retries < MAX_GC_RETRIES) { - ri->gc_retries += 1; - dbg_budg("run GC, retries %d of %d", - ri->gc_retries, MAX_GC_RETRIES); + dbg_budg("new liability %lld (not shrinked)", liab2); - ri->try_gc = 0; + /* Liability did not shrink again, try GC */ + dbg_budg("Run GC"); err = run_gc(c); if (!err) return -EAGAIN; - if (err == -EAGAIN) { - dbg_budg("GC asked to commit"); - err = ubifs_run_commit(c); - if (err) - return err; - return -EAGAIN; - } - - if (err != -ENOSPC) + if (err != -EAGAIN && err != -ENOSPC) + /* Some real error happened */ return err; - /* - * GC could not make any progress. If this is the first time, - * then it makes sense to try to commit, because it might make - * some dirty space. - */ - dbg_budg("GC returned -ENOSPC, retries %d", - ri->nospc_retries); - if (ri->nospc_retries >= MAX_NOSPC_RETRIES) - return err; - ri->nospc_retries += 1; - } - - /* Neither GC nor write-back helped, try to commit */ - if (ri->cmt_retries < MAX_CMT_RETRIES) { - ri->cmt_retries += 1; - dbg_budg("run commit, retries %d of %d", - ri->cmt_retries, MAX_CMT_RETRIES); + dbg_budg("Run commit (retries %d)", retries); err = ubifs_run_commit(c); if (err) return err; - return -EAGAIN; - } + } while (retries++ < MAX_MKSPC_RETRIES); + return -ENOSPC; } /** - * ubifs_calc_min_idx_lebs - calculate amount of eraseblocks for the index. + * ubifs_calc_min_idx_lebs - calculate amount of LEBs for the index. * @c: UBIFS file-system description object * - * This function calculates and returns the number of eraseblocks which should - * be kept for index usage. + * This function calculates and returns the number of LEBs which should be kept + * for index usage. */ int ubifs_calc_min_idx_lebs(struct ubifs_info *c) { - int ret; - uint64_t idx_size; + int idx_lebs; + long long idx_size; idx_size = c->old_idx_sz + c->budg_idx_growth + c->budg_uncommitted_idx; - /* And make sure we have thrice the index size of space reserved */ - idx_size = idx_size + (idx_size << 1); - + idx_size += idx_size << 1; /* * We do not maintain 'old_idx_size' as 'old_idx_lebs'/'old_idx_bytes' * pair, nor similarly the two variables for the new index size, so we * have to do this costly 64-bit division on fast-path. */ - if (do_div(idx_size, c->leb_size - c->max_idx_node_sz)) - ret = idx_size + 1; - else - ret = idx_size; + idx_lebs = div_u64(idx_size + c->idx_leb_size - 1, c->idx_leb_size); /* * The index head is not available for the in-the-gaps method, so add an * extra LEB to compensate. */ - ret += 1; - /* - * At present the index needs at least 2 LEBs: one for the index head - * and one for in-the-gaps method (which currently does not cater for - * the index head and so excludes it from consideration). - */ - if (ret < 2) - ret = 2; - return ret; + idx_lebs += 1; + if (idx_lebs < MIN_INDEX_LEBS) + idx_lebs = MIN_INDEX_LEBS; + return idx_lebs; } /** @@ -363,7 +270,7 @@ long long ubifs_calc_available(const struct ubifs_info *c, int min_idx_lebs) */ static int can_use_rp(struct ubifs_info *c) { - if (current->fsuid == c->rp_uid || capable(CAP_SYS_RESOURCE) || + if (current_fsuid() == c->rp_uid || capable(CAP_SYS_RESOURCE) || (c->rp_gid != 0 && in_group_p(c->rp_gid))) return 1; return 0; @@ -373,23 +280,23 @@ static int can_use_rp(struct ubifs_info *c) * do_budget_space - reserve flash space for index and data growth. * @c: UBIFS file-system description object * - * This function makes sure UBIFS has enough free eraseblocks for index growth - * and data. + * This function makes sure UBIFS has enough free LEBs for index growth and + * data. * * When budgeting index space, UBIFS reserves thrice as many LEBs as the index * would take if it was consolidated and written to the flash. This guarantees * that the "in-the-gaps" commit method always succeeds and UBIFS will always * be able to commit dirty index. So this function basically adds amount of * budgeted index space to the size of the current index, multiplies this by 3, - * and makes sure this does not exceed the amount of free eraseblocks. + * and makes sure this does not exceed the amount of free LEBs. * * Notes about @c->min_idx_lebs and @c->lst.idx_lebs variables: * o @c->lst.idx_lebs is the number of LEBs the index currently uses. It might * be large, because UBIFS does not do any index consolidation as long as * there is free space. IOW, the index may take a lot of LEBs, but the LEBs * will contain a lot of dirt. - * o @c->min_idx_lebs is the the index presumably takes. IOW, the index may be - * consolidated to take up to @c->min_idx_lebs LEBs. + * o @c->min_idx_lebs is the number of LEBS the index presumably takes. IOW, + * the index may be consolidated to take up to @c->min_idx_lebs LEBs. * * This function returns zero in case of success, and %-ENOSPC in case of * failure. @@ -414,19 +321,21 @@ static int do_budget_space(struct ubifs_info *c) * @c->lst.empty_lebs + @c->freeable_cnt + @c->idx_gc_cnt - * @c->lst.taken_empty_lebs * - * @empty_lebs are available because they are empty. @freeable_cnt are - * available because they contain only free and dirty space and the - * index allocation always occurs after wbufs are synch'ed. - * @idx_gc_cnt are available because they are index LEBs that have been - * garbage collected (including trivial GC) and are awaiting the commit - * before they can be unmapped - note that the in-the-gaps method will - * grab these if it needs them. @taken_empty_lebs are empty_lebs that - * have already been allocated for some purpose (also includes those - * LEBs on the @idx_gc list). + * @c->lst.empty_lebs are available because they are empty. + * @c->freeable_cnt are available because they contain only free and + * dirty space, @c->idx_gc_cnt are available because they are index + * LEBs that have been garbage collected and are awaiting the commit + * before they can be used. And the in-the-gaps method will grab these + * if it needs them. @c->lst.taken_empty_lebs are empty LEBs that have + * already been allocated for some purpose. * - * Note, @taken_empty_lebs may temporarily be higher by one because of - * the way we serialize LEB allocations and budgeting. See a comment in - * 'ubifs_find_free_space()'. + * Note, @c->idx_gc_cnt is included to both @c->lst.empty_lebs (because + * these LEBs are empty) and to @c->lst.taken_empty_lebs (because they + * are taken until after the commit). + * + * Note, @c->lst.taken_empty_lebs may temporarily be higher by one + * because of the way we serialize LEB allocations and budgeting. See a + * comment in 'ubifs_find_free_space()'. */ lebs = c->lst.empty_lebs + c->freeable_cnt + c->idx_gc_cnt - c->lst.taken_empty_lebs; @@ -528,8 +437,7 @@ static int calc_dd_growth(const struct ubifs_info *c, int ubifs_budget_space(struct ubifs_info *c, struct ubifs_budget_req *req) { int uninitialized_var(cmt_retries), uninitialized_var(wb_retries); - int err, idx_growth, data_growth, dd_growth; - struct retries_info ri; + int err, idx_growth, data_growth, dd_growth, retried = 0; ubifs_assert(req->new_page <= 1); ubifs_assert(req->dirtied_page <= 1); @@ -547,7 +455,6 @@ int ubifs_budget_space(struct ubifs_info *c, struct ubifs_budget_req *req) if (!data_growth && !dd_growth) return 0; idx_growth = calc_idx_growth(c, req); - memset(&ri, 0, sizeof(struct retries_info)); again: spin_lock(&c->space_lock); @@ -585,12 +492,17 @@ again: return err; } - err = make_free_space(c, &ri); + err = make_free_space(c); + cond_resched(); if (err == -EAGAIN) { dbg_budg("try again"); - cond_resched(); goto again; } else if (err == -ENOSPC) { + if (!retried) { + retried = 1; + dbg_budg("-ENOSPC, but anyway try once again"); + goto again; + } dbg_budg("FS is full, -ENOSPC"); c->nospace = 1; if (can_use_rp(c) || c->rp_size == 0) @@ -664,7 +576,7 @@ void ubifs_release_budget(struct ubifs_info *c, struct ubifs_budget_req *req) * @c: UBIFS file-system description object * * This function converts budget which was allocated for a new page of data to - * the budget of changing an existing page of data. The latter is smaller then + * the budget of changing an existing page of data. The latter is smaller than * the former, so this function only does simple re-calculation and does not * involve any write-back. */ @@ -689,7 +601,7 @@ void ubifs_convert_page_budget(struct ubifs_info *c) * * This function releases budget corresponding to a dirty inode. It is usually * called when after the inode has been written to the media and marked as - * clean. + * clean. It also causes the "no space" flags to be cleared. */ void ubifs_release_dirty_inode_budget(struct ubifs_info *c, struct ubifs_inode *ui) @@ -697,6 +609,7 @@ void ubifs_release_dirty_inode_budget(struct ubifs_info *c, struct ubifs_budget_req req; memset(&req, 0, sizeof(struct ubifs_budget_req)); + /* The "no space" flags will be cleared because dd_growth is > 0 */ req.dd_growth = c->inode_budget + ALIGN(ui->data_len, 8); ubifs_release_budget(c, &req); } @@ -710,9 +623,9 @@ void ubifs_release_dirty_inode_budget(struct ubifs_info *c, * user-space. User-space application tend to expect that if the file-system * (e.g., via the 'statfs()' call) reports that it has N bytes available, they * are able to write a file of size N. UBIFS attaches node headers to each data - * node and it has to write indexind nodes as well. This introduces additional - * overhead, and UBIFS it has to report sligtly less free space to meet the - * above expectetion. + * node and it has to write indexing nodes as well. This introduces additional + * overhead, and UBIFS has to report slightly less free space to meet the above + * expectations. * * This function assumes free space is made up of uncompressed data nodes and * full index nodes (one per data node, tripled because we always allow enough @@ -721,57 +634,75 @@ void ubifs_release_dirty_inode_budget(struct ubifs_info *c, * Note, the calculation is pessimistic, which means that most of the time * UBIFS reports less space than it actually has. */ -long long ubifs_reported_space(const struct ubifs_info *c, uint64_t free) +long long ubifs_reported_space(const struct ubifs_info *c, long long free) { - int divisor, factor; + int divisor, factor, f; /* * Reported space size is @free * X, where X is UBIFS block size * divided by UBIFS block size + all overhead one data block * introduces. The overhead is the node header + indexing overhead. * - * Indexing overhead is calculations are based on the following - * formula: I = N/(f - 1) + 1, where I - number of indexing nodes, N - - * number of data nodes, f - fanout. Because effective UBIFS fanout is - * twice as less than maximum fanout, we assume that each data node + * Indexing overhead calculations are based on the following formula: + * I = N/(f - 1) + 1, where I - number of indexing nodes, N - number + * of data nodes, f - fanout. Because effective UBIFS fanout is twice + * as less than maximum fanout, we assume that each data node * introduces 3 * @c->max_idx_node_sz / (@c->fanout/2 - 1) bytes. - * Note, the multiplier 3 is because UBIFS reseves thrice as more space + * Note, the multiplier 3 is because UBIFS reserves thrice as more space * for the index. */ + f = c->fanout > 3 ? c->fanout >> 1 : 2; factor = UBIFS_BLOCK_SIZE; divisor = UBIFS_MAX_DATA_NODE_SZ; - divisor += (c->max_idx_node_sz * 3) / ((c->fanout >> 1) - 1); + divisor += (c->max_idx_node_sz * 3) / (f - 1); free *= factor; - do_div(free, divisor); - return free; + return div_u64(free, divisor); } /** - * ubifs_budg_get_free_space - return amount of free space. + * ubifs_get_free_space_nolock - return amount of free space. * @c: UBIFS file-system description object * - * This function returns amount of free space on the file-system. + * This function calculates amount of free space to report to user-space. + * + * Because UBIFS may introduce substantial overhead (the index, node headers, + * alignment, wastage at the end of LEBs, etc), it cannot report real amount of + * free flash space it has (well, because not all dirty space is reclaimable, + * UBIFS does not actually know the real amount). If UBIFS did so, it would + * bread user expectations about what free space is. Users seem to accustomed + * to assume that if the file-system reports N bytes of free space, they would + * be able to fit a file of N bytes to the FS. This almost works for + * traditional file-systems, because they have way less overhead than UBIFS. + * So, to keep users happy, UBIFS tries to take the overhead into account. */ -long long ubifs_budg_get_free_space(struct ubifs_info *c) +long long ubifs_get_free_space_nolock(struct ubifs_info *c) { - int min_idx_lebs; + int rsvd_idx_lebs, lebs; long long available, outstanding, free; - spin_lock(&c->space_lock); - min_idx_lebs = ubifs_calc_min_idx_lebs(c); + ubifs_assert(c->min_idx_lebs == ubifs_calc_min_idx_lebs(c)); outstanding = c->budg_data_growth + c->budg_dd_growth; + available = ubifs_calc_available(c, c->min_idx_lebs); /* - * Force the amount available to the total size reported if the used - * space is zero. + * When reporting free space to user-space, UBIFS guarantees that it is + * possible to write a file of free space size. This means that for + * empty LEBs we may use more precise calculations than + * 'ubifs_calc_available()' is using. Namely, we know that in empty + * LEBs we would waste only @c->leb_overhead bytes, not @c->dark_wm. + * Thus, amend the available space. + * + * Note, the calculations below are similar to what we have in + * 'do_budget_space()', so refer there for comments. */ - if (c->lst.total_used <= UBIFS_INO_NODE_SZ && !outstanding) { - spin_unlock(&c->space_lock); - return (long long)c->block_cnt << UBIFS_BLOCK_SHIFT; - } - - available = ubifs_calc_available(c, min_idx_lebs); - spin_unlock(&c->space_lock); + if (c->min_idx_lebs > c->lst.idx_lebs) + rsvd_idx_lebs = c->min_idx_lebs - c->lst.idx_lebs; + else + rsvd_idx_lebs = 0; + lebs = c->lst.empty_lebs + c->freeable_cnt + c->idx_gc_cnt - + c->lst.taken_empty_lebs; + lebs -= rsvd_idx_lebs; + available += lebs * (c->dark_wm - c->leb_overhead); if (available > outstanding) free = ubifs_reported_space(c, available - outstanding); @@ -779,3 +710,21 @@ long long ubifs_budg_get_free_space(struct ubifs_info *c) free = 0; return free; } + +/** + * ubifs_get_free_space - return amount of free space. + * @c: UBIFS file-system description object + * + * This function calculates and returns amount of free space to report to + * user-space. + */ +long long ubifs_get_free_space(struct ubifs_info *c) +{ + long long free; + + spin_lock(&c->space_lock); + free = ubifs_get_free_space_nolock(c); + spin_unlock(&c->space_lock); + + return free; +}